Fixup Pip and lock handling of use_system_time.

In the Pip case, do not mix the associated env vars into the PEX, just
pass via env var - this need not effect disk layout / potentially double
the number of Pip venvs. In the lock case, ensure old locks use system
time as they have been; only have new locks use this new feature
(unconditionally).

pex/cache/dirs.py

@@ -136,7 +136,7 @@ def iter_transitive_dependents(self):
 
     PIP = Value(
         "pip",
-        version=0,
+        version=1,
         name="Pip Versions",
         description="Isolated Pip caches and Pip PEXes Pex uses to resolve distributions.",
     )

pex/pip/installation.py

@@ -55,10 +55,8 @@ def _pip_installation(
 
             isolated_pip_builder = PEXBuilder(path=chroot.work_dir)
             isolated_pip_builder.info.venv = True
-            # Allow REPRODUCIBLE_BUILDS_ENV PYTHONHASHSEED env var to take effect.
+            # Allow REPRODUCIBLE_BUILDS_ENV PYTHONHASHSEED env var to take effect if needed.
             isolated_pip_builder.info.venv_hermetic_scripts = False
-            if not use_system_time:
-                isolated_pip_builder.info.inject_env = REPRODUCIBLE_BUILDS_ENV
             for dist_location in iter_distribution_locations():
                 isolated_pip_builder.add_dist_location(dist=dist_location)
             with named_temporary_file(prefix="", suffix=".py", mode="w") as fp:
@@ -83,7 +81,11 @@ def _pip_installation(
             isolated_pip_builder.freeze()
     pip_cache = os.path.join(pip_root, "pip_cache")
     pip_pex = ensure_venv(PEX(pip_pex_path, interpreter=pip_interpreter))
-    pip_venv = PipVenv(venv_dir=pip_pex.venv_dir, execute_args=tuple(pip_pex.execute_args()))
+    pip_venv = PipVenv(
+        venv_dir=pip_pex.venv_dir,
+        execute_env=REPRODUCIBLE_BUILDS_ENV if not use_system_time else {},
+        execute_args=tuple(pip_pex.execute_args()),
+    )
     return Pip(pip=pip_venv, version=version, pip_cache=pip_cache)
 
 

pex/pip/tool.py

@@ -272,6 +272,7 @@ def analyze(self, line):
 @attr.s(frozen=True)
 class PipVenv(object):
     venv_dir = attr.ib()  # type: str
+    execute_env = attr.ib()  # type: Mapping[str, str]
     _execute_args = attr.ib()  # type: Tuple[str, ...]
 
     def execute_args(self, *args):
@@ -431,6 +432,7 @@ def _spawn_pip_isolated(
                 popen_kwargs["stdout"] = sys.stderr.fileno()
             popen_kwargs.update(stderr=subprocess.PIPE)
 
+            env.update(self._pip.execute_env)
             args = self._pip.execute_args(*command)
 
             rendered_env = " ".join(

pex/resolve/lockfile/json_codec.py

@@ -352,6 +352,10 @@ def assemble_tag(
             prefer_older_binary=get("prefer_older_binary", bool),
             use_pep517=get("use_pep517", bool, optional=True),
             build_isolation=get("build_isolation", bool),
+            # N.B.: Although locks are now always generated under SOURCE_DATE_EPOCH=fixed and
+            # PYTHONHASHSEED=0 (aka: `use_system_time=False`), that did not use to be the case. In
+            # those old locks there was no "use_system_time" field.
+            use_system_time=get("use_system_time", bool, optional=True) or True,
         ),
         transitive=get("transitive", bool),
         excluded=excluded,
@@ -399,6 +403,7 @@ def as_json_data(
         "prefer_older_binary": lockfile.prefer_older_binary,
         "use_pep517": lockfile.use_pep517,
         "build_isolation": lockfile.build_isolation,
+        "use_system_time": lockfile.use_system_time,
         "transitive": lockfile.transitive,
         "excluded": [str(exclude) for exclude in lockfile.excluded],
         "overridden": [str(override) for override in lockfile.overridden],

pex/resolve/lockfile/model.py

@@ -106,6 +106,7 @@ def extract_requirement(req):
             prefer_older_binary=build_configuration.prefer_older_binary,
             use_pep517=build_configuration.use_pep517,
             build_isolation=build_configuration.build_isolation,
+            use_system_time=build_configuration.use_system_time,
             transitive=transitive,
             excluded=SortedTuple(excluded),
             overridden=SortedTuple(overridden),
@@ -130,6 +131,7 @@ def extract_requirement(req):
     prefer_older_binary = attr.ib()  # type: bool
     use_pep517 = attr.ib()  # type: Optional[bool]
     build_isolation = attr.ib()  # type: bool
+    use_system_time = attr.ib()  # type: bool
     transitive = attr.ib()  # type: bool
     excluded = attr.ib()  # type: SortedTuple[Requirement]
     overridden = attr.ib()  # type: SortedTuple[Requirement]
@@ -147,7 +149,7 @@ def build_configuration(self):
             prefer_older_binary=self.prefer_older_binary,
             use_pep517=self.use_pep517,
             build_isolation=self.build_isolation,
-            use_system_time=False,
+            use_system_time=self.use_system_time,
         )
 
     def dependency_configuration(self):

tests/integration/cli/commands/test_export.py

@@ -57,6 +57,7 @@
     prefer_older_binary=False,
     use_pep517=None,
     build_isolation=True,
+    use_system_time=False,
     transitive=True,
     excluded=SortedTuple(),
     overridden=SortedTuple(),