Fix the "new install" case of issue #2037

news/2037.bugfix

@@ -0,0 +1 @@
+Checkout the correct branch when doing an editable Git install.

src/pip/_internal/vcs/git.py

@@ -77,6 +77,20 @@ def get_git_version(self):
         version = '.'.join(version.split('.')[:3])
         return parse_version(version)
 
+    def get_branch(self, location):
+        """
+        Return the current branch, or None if HEAD isn't at a branch
+        (e.g. detached HEAD).
+        """
+        args = ['rev-parse', '--abbrev-ref', 'HEAD']
+        output = self.run_command(args, show_stdout=False, cwd=location)
+        branch = output.strip()
+
+        if branch == 'HEAD':
+            return None
+
+        return branch
+
     def export(self, location):
         """Export the Git repository at the url to the destination location"""
         if not location.endswith('/'):
@@ -91,8 +105,8 @@ def export(self, location):
 
     def get_revision_sha(self, dest, rev):
         """
-        Return a commit hash for the given revision if it names a remote
-        branch or tag.  Otherwise, return None.
+        Return (sha_or_none, is_branch), where sha_or_none is a commit hash
+        if the revision names a remote branch or tag, otherwise None.
 
         Args:
           dest: the repository directory.
@@ -115,7 +129,13 @@ def get_revision_sha(self, dest, rev):
         branch_ref = 'refs/remotes/origin/{}'.format(rev)
         tag_ref = 'refs/tags/{}'.format(rev)
 
-        return refs.get(branch_ref) or refs.get(tag_ref)
+        sha = refs.get(branch_ref)
+        if sha is not None:
+            return (sha, True)
+
+        sha = refs.get(tag_ref)
+
+        return (sha, False)
 
     def resolve_revision(self, dest, url, rev_options):
         """
@@ -126,10 +146,13 @@ def resolve_revision(self, dest, url, rev_options):
           rev_options: a RevOptions object.
         """
         rev = rev_options.arg_rev
-        sha = self.get_revision_sha(dest, rev)
+        sha, is_branch = self.get_revision_sha(dest, rev)
 
         if sha is not None:
-            return rev_options.make_new(sha)
+            rev_options = rev_options.make_new(sha)
+            rev_options.branch_name = rev if is_branch else None
+
+            return rev_options
 
         # Do not show a warning for the common case of something that has
         # the form of a Git commit hash.
@@ -177,10 +200,20 @@ def fetch_new(self, dest, url, rev_options):
         if rev_options.rev:
             # Then a specific revision was requested.
             rev_options = self.resolve_revision(dest, url, rev_options)
-            # Only do a checkout if the current commit id doesn't match
-            # the requested revision.
-            if not self.is_commit_id_equal(dest, rev_options.rev):
-                cmd_args = ['checkout', '-q'] + rev_options.to_args()
+            branch_name = getattr(rev_options, 'branch_name', None)
+            if branch_name is None:
+                # Only do a checkout if the current commit id doesn't match
+                # the requested revision.
+                if not self.is_commit_id_equal(dest, rev_options.rev):
+                    cmd_args = ['checkout', '-q'] + rev_options.to_args()
+                    self.run_command(cmd_args, cwd=dest)
+            elif self.get_branch(dest) != branch_name:
+                # Then a specific branch was requested, and that branch
+                # is not yet checked out.
+                track_branch = 'origin/{}'.format(branch_name)
+                cmd_args = [
+                    'checkout', '-b', branch_name, '--track', track_branch,
+                ]
                 self.run_command(cmd_args, cwd=dest)
 
         #: repo may contain submodules

tests/functional/test_install_vcs_git.py

@@ -10,15 +10,32 @@
 from tests.lib.local_repos import local_checkout
 
 
+def _get_editable_repo_dir(script, package_name):
+    """
+    Return the repository directory for an editable install.
+    """
+    return script.venv_path / 'src' / package_name
+
+
 def _get_editable_branch(script, package_name):
     """
     Return the current branch of an editable install.
     """
-    repo_dir = script.venv_path / 'src' / package_name
+    repo_dir = _get_editable_repo_dir(script, package_name)
     result = script.run(
         'git', 'rev-parse', '--abbrev-ref', 'HEAD', cwd=repo_dir
     )
+    return result.stdout.strip()
+
 
+def _get_branch_remote(script, package_name, branch):
+    """
+
+    """
+    repo_dir = _get_editable_repo_dir(script, package_name)
+    result = script.run(
+        'git', 'config', 'branch.{}.remote'.format(branch), cwd=repo_dir
+    )
     return result.stdout.strip()
 
 
@@ -363,7 +380,69 @@ def test_git_works_with_editable_non_origin_repo(script):
     assert "version-pkg==0.1" in result.stdout
 
 
-def test_editable_non_master_default_branch(script):
+def test_editable__no_revision(script):
+    """
+    Test a basic install in editable mode specifying no revision.
+    """
+    version_pkg_path = _create_test_package(script)
+    _install_version_pkg_only(script, version_pkg_path)
+
+    branch = _get_editable_branch(script, 'version-pkg')
+    assert branch == 'master'
+
+    remote = _get_branch_remote(script, 'version-pkg', 'master')
+    assert remote == 'origin'
+
+
+def test_editable__branch_with_sha_same_as_default(script):
+    """
+    Test installing in editable mode a branch whose sha matches the sha
+    of the default branch, but is different from the default branch.
+    """
+    version_pkg_path = _create_test_package(script)
+    # Create a second branch with the same SHA.
+    script.run(
+        'git', 'branch', 'develop', expect_stderr=True,
+        cwd=version_pkg_path,
+    )
+    _install_version_pkg_only(
+        script, version_pkg_path, rev='develop', expect_stderr=True
+    )
+
+    branch = _get_editable_branch(script, 'version-pkg')
+    assert branch == 'develop'
+
+    remote = _get_branch_remote(script, 'version-pkg', 'develop')
+    assert remote == 'origin'
+
+
+def test_editable__branch_with_sha_different_from_default(script):
+    """
+    Test installing in editable mode a branch whose sha is different from
+    the sha of the default branch.
+    """
+    version_pkg_path = _create_test_package(script)
+    # Create a second branch.
+    script.run(
+        'git', 'branch', 'develop', expect_stderr=True,
+        cwd=version_pkg_path,
+    )
+    # Add another commit to the master branch to give it a different sha.
+    _change_test_package_version(script, version_pkg_path)
+
+    version = _install_version_pkg(
+        script, version_pkg_path, rev='develop', expect_stderr=True
+    )
+    assert version == '0.1'
+
+    branch = _get_editable_branch(script, 'version-pkg')
+    assert branch == 'develop'
+
+    remote = _get_branch_remote(script, 'version-pkg', 'develop')
+    assert remote == 'origin'
+
+
+def test_editable__non_master_default_branch(script):
     """
     Test the branch you get after an editable install from a remote repo
     with a non-master default branch.
@@ -376,8 +455,9 @@ def test_editable_non_master_default_branch(script):
         cwd=version_pkg_path,
     )
     _install_version_pkg_only(script, version_pkg_path)
+
     branch = _get_editable_branch(script, 'version-pkg')
-    assert 'release' == branch
+    assert branch == 'release'
 
 
 def test_reinstalling_works_with_editable_non_master_branch(script):

tests/functional/test_vcs_git.py

@@ -37,9 +37,9 @@ def add_commits(script, dest, count):
     return shas
 
 
-def check_rev(repo_dir, rev, expected_sha):
+def check_rev(repo_dir, rev, expected):
     git = Git()
-    assert git.get_revision_sha(repo_dir, rev) == expected_sha
+    assert git.get_revision_sha(repo_dir, rev) == expected
 
 
 def test_git_dir_ignored():
@@ -70,6 +70,27 @@ def test_git_work_tree_ignored():
         git.run_command(['status', temp_dir], extra_environ=env, cwd=temp_dir)
 
 
+def test_get_branch(script, tmpdir):
+    repo_dir = str(tmpdir)
+    script.run('git', 'init', cwd=repo_dir)
+    sha = do_commit(script, repo_dir)
+
+    git = Git()
+    assert git.get_branch(repo_dir) == 'master'
+
+    # Switch to a branch with the same SHA as "master" but whose name
+    # is alphabetically after.
+    script.run(
+        'git', 'checkout', '-b', 'release', cwd=repo_dir,
+        expect_stderr=True,
+    )
+    assert git.get_branch(repo_dir) == 'release'
+
+    # Also test the detached HEAD case.
+    script.run('git', 'checkout', sha, cwd=repo_dir, expect_stderr=True)
+    assert git.get_branch(repo_dir) is None
+
+
 def test_get_revision_sha(script):
     with TempDirectory(kind="testing") as temp:
         repo_dir = temp.path
@@ -102,9 +123,9 @@ def test_get_revision_sha(script):
         script.run('git', 'tag', 'aaa/v1.0', head_sha, cwd=repo_dir)
         script.run('git', 'tag', 'zzz/v1.0', head_sha, cwd=repo_dir)
 
-        check_rev(repo_dir, 'v1.0', tag_sha)
-        check_rev(repo_dir, 'v2.0', tag_sha)
-        check_rev(repo_dir, 'origin-branch', origin_sha)
+        check_rev(repo_dir, 'v1.0', (tag_sha, False))
+        check_rev(repo_dir, 'v2.0', (tag_sha, False))
+        check_rev(repo_dir, 'origin-branch', (origin_sha, True))
 
         ignored_names = [
             # Local branches should be ignored.
@@ -122,7 +143,7 @@ def test_get_revision_sha(script):
             'does-not-exist',
         ]
         for name in ignored_names:
-            check_rev(repo_dir, name, None)
+            check_rev(repo_dir, name, (None, False))
 
 
 @pytest.mark.network

tests/unit/test_vcs.py

@@ -109,7 +109,7 @@ def test_git_get_src_requirements(git, dist):
 
 @patch('pip._internal.vcs.git.Git.get_revision_sha')
 def test_git_resolve_revision_rev_exists(get_sha_mock):
-    get_sha_mock.return_value = '123456'
+    get_sha_mock.return_value = ('123456', False)
     git = Git()
     rev_options = git.make_rev_options('develop')
 
@@ -120,7 +120,7 @@ def test_git_resolve_revision_rev_exists(get_sha_mock):
 
 @patch('pip._internal.vcs.git.Git.get_revision_sha')
 def test_git_resolve_revision_rev_not_found(get_sha_mock):
-    get_sha_mock.return_value = None
+    get_sha_mock.return_value = (None, False)
     git = Git()
     rev_options = git.make_rev_options('develop')
 
@@ -131,7 +131,7 @@ def test_git_resolve_revision_rev_not_found(get_sha_mock):
 
 @patch('pip._internal.vcs.git.Git.get_revision_sha')
 def test_git_resolve_revision_not_found_warning(get_sha_mock, caplog):
-    get_sha_mock.return_value = None
+    get_sha_mock.return_value = (None, False)
     git = Git()
 
     url = 'git+https://git.example.com'