Use --depth=1 when checking out git repositories

In most uses of pip's git backend, we don't need the full git history -
only the target head/branch/tag.  This change adds --depth=1 to git
fetch and clone commands.

NB: "Shallow" checkouts are not supported from arbitrary git commits, so
this change removes the ability to install from git SHA1 commit IDs.
Tags and branches continue to be supported.

Fixes pypa#2432

docs/reference/pip_install.rst

@@ -180,11 +180,10 @@ Here are the supported forms::
     [-e] git+ssh://git.myproject.org/MyProject#egg=MyProject
     -e [email protected]:MyProject#egg=MyProject
 
-Passing branch names, a commit hash or a tag name is possible like so::
+Passing branch names or a tag name is possible like so::
 
     [-e] git://git.myproject.org/MyProject.git@master#egg=MyProject
     [-e] git://git.myproject.org/[email protected]#egg=MyProject
-    [-e] git://git.myproject.org/MyProject.git@da39a3ee5e6b4b0d3255bfef95601890afd80709#egg=MyProject
 
 Mercurial
 ~~~~~~~~~
@@ -506,5 +505,3 @@ Examples
  ::
 
   $ pip install --pre SomePackage
-
-

pip/vcs/git.py

@@ -85,14 +85,14 @@ def switch(self, dest, url, rev_options):
         call_subprocess(
             [self.cmd, 'config', 'remote.origin.url', url], cwd=dest)
         call_subprocess(
-            [self.cmd, 'checkout', '-q'] + rev_options, cwd=dest)
-
+            [self.cmd, 'fetch', '-q', '--depth', '1',
+             'origin', '+%s' % rev_options[0]] + rev_options[1:], cwd=dest)
         self.update_submodules(dest)
 
     def update(self, dest, rev_options):
         # First fetch changes from the default remote
         call_subprocess([self.cmd, 'fetch', '-q'], cwd=dest)
-        # Then reset to wanted revision (maby even origin/master)
+        # Then reset to wanted revision (maybe even origin/master)
         if rev_options:
             rev_options = self.check_rev_options(
                 rev_options[0], dest, rev_options,
@@ -107,27 +107,19 @@ def update(self, dest, rev_options):
     def obtain(self, dest):
         url, rev = self.get_url_rev()
         if rev:
-            rev_options = [rev]
             rev_display = ' (to %s)' % rev
         else:
-            rev_options = ['origin/master']
+            rev = 'master'
             rev_display = ''
-        if self.check_destination(dest, url, rev_options, rev_display):
+        if self.check_destination(dest, url, [rev], rev_display):
             logger.info(
                 'Cloning %s%s to %s', url, rev_display, display_path(dest),
             )
-            call_subprocess([self.cmd, 'clone', '-q', url, dest])
-
-            if rev:
-                rev_options = self.check_rev_options(rev, dest, rev_options)
-                # Only do a checkout if rev_options differs from HEAD
-                if not self.get_revision(dest).startswith(rev_options[0]):
-                    call_subprocess(
-                        [self.cmd, 'checkout', '-q'] + rev_options,
-                        cwd=dest,
-                    )
-            #: repo may contain submodules
-            self.update_submodules(dest)
+            call_subprocess([self.cmd, 'clone', '-q',
+                             '--branch', rev,
+                             '--depth', '1',
+                             '--recurse-submodules',
+                             url, dest])
 
     def get_url(self, location):
         url = call_subprocess(
@@ -178,7 +170,7 @@ def get_src_requirement(self, dist, location, find_tags):
 
         if current_rev in names_by_commit:
             # It's a tag or branch.
-            name = names_by_commit[current_rev]
+            current_rev = name = names_by_commit[current_rev]
             full_egg_name = (
                 '%s-%s' % (egg_project_name, self.translate_egg_surname(name))
             )

tests/functional/test_install_vcs.py

@@ -30,7 +30,8 @@ def test_install_noneditable_git(script, tmpdir):
     result = script.pip(
         'install',
         'git+https://github.com/pypa/pip-test-package.git'
-        '@0.1.1#egg=pip-test-package'
+        '@0.1.1#egg=pip-test-package',
+        expect_stderr=True,
     )
     egg_info_folder = (
         script.site_packages /
@@ -42,26 +43,6 @@ def test_install_noneditable_git(script, tmpdir):
     assert egg_info_folder in result.files_created, str(result)
 
 
-@pytest.mark.network
-def test_git_with_sha1_revisions(script):
-    """
-    Git backend should be able to install from SHA1 revisions
-    """
-    version_pkg_path = _create_test_package(script)
-    _change_test_package_version(script, version_pkg_path)
-    sha1 = script.run(
-        'git', 'rev-parse', 'HEAD~1',
-        cwd=version_pkg_path,
-    ).stdout.strip()
-    script.pip(
-        'install', '-e',
-        '%s@%s#egg=version_pkg' %
-        ('git+file://' + version_pkg_path.abspath.replace('\\', '/'), sha1)
-    )
-    version = script.run('version_pkg')
-    assert '0.1' in version.stdout, version.stdout
-
-
 @pytest.mark.network
 def test_git_with_branch_name_as_revision(script):
     """
@@ -96,7 +77,8 @@ def test_git_with_tag_name_as_revision(script):
     _change_test_package_version(script, version_pkg_path)
     script.pip(
         'install', '-e', '%s@test_tag#egg=version_pkg' %
-        ('git+file://' + version_pkg_path.abspath.replace('\\', '/'))
+        ('git+file://' + version_pkg_path.abspath.replace('\\', '/')),
+        expect_stderr=True,
     )
     version = script.run('version_pkg')
     assert '0.1' in version.stdout
@@ -210,7 +192,7 @@ def test_git_with_ambiguous_revs(script):
         (version_pkg_path.abspath.replace('\\', '/'))
     )
     script.run('git', 'tag', '0.1', cwd=version_pkg_path)
-    result = script.pip('install', '-e', package_url)
+    result = script.pip('install', '-e', package_url, expect_stderr=True)
     assert 'Could not find a tag or branch' not in result.stdout
     # it is 'version-pkg' instead of 'version_pkg' because
     # egg-link name is version-pkg.egg-link because it is a single .py module

tests/functional/test_install_vcs_git.py

@@ -96,8 +96,10 @@ def test_check_submodule_addition(script):
     """
     module_path, submodule_path = _create_test_package_with_submodule(script)
 
+    # expect error because git may write to stderr
     install_result = script.pip(
-        'install', '-e', 'git+' + module_path + '#egg=version_pkg'
+        'install', '-e', 'git+' + module_path + '#egg=version_pkg',
+        expect_error=True,
     )
     assert (
         script.venv / 'src/version-pkg/testpkg/static/testfile'

tests/unit/test_vcs.py

@@ -34,7 +34,7 @@ def test_git_get_src_requirements():
 
     assert ret == ''.join([
         'git+http://github.com/pypa/pip-test-package',
-        '@5547fa909e83df8bd743d3978d6667497983a4b7',
+        '@bar',
         '#egg=pip_test_package-bar'
     ])