Bug 1762050: Use original topobjdir for PGO build virtualenv r=glandium

The PGO-specific objdir is meant for the PGO build artifacts.
The python virtualenvs just exist for the host, so there's no need to
scope them. Besides, the existing virtualenv infrastructure doesn't know
how to distinguish between "main 'build' site" and "PGO 'build' site",
which is why it raised this "out-of-date" error.

Differential Revision: https://phabricator.services.mozilla.com/D142373

python/mozbuild/mozbuild/build_commands.py

@@ -185,6 +185,7 @@ def build(
             keep_going=keep_going,
             mach_context=command_context._mach_context,
             append_env=append_env,
+            virtualenv_topobjdir=orig_topobjdir,
         )
         if status != 0:
             return status
@@ -208,7 +209,7 @@ def build(
             )
         pgo_env["JARLOG_FILE"] = mozpath.join(orig_topobjdir, "jarlog/en-US.log")
         pgo_cmd = [
-            instr.virtualenv_manager.python_path,
+            command_context.virtualenv_manager.python_path,
             mozpath.join(command_context.topsrcdir, "build/pgo/profileserver.py"),
         ]
         subprocess.check_call(pgo_cmd, cwd=instr.topobjdir, env=pgo_env)

python/mozbuild/mozbuild/controller/building.py

@@ -1222,6 +1222,7 @@ class BuildDriver(MozbuildObject):
         keep_going=False,
         mach_context=None,
         append_env=None,
+        virtualenv_topobjdir=None,
     ):
         """Invoke the build backend.
 
@@ -1299,6 +1300,7 @@ class BuildDriver(MozbuildObject):
                     buildstatus_messages=True,
                     line_handler=output.on_line,
                     append_env=append_env,
+                    virtualenv_topobjdir=virtualenv_topobjdir,
                 )
 
                 if config_rc != 0:
@@ -1637,6 +1639,7 @@ class BuildDriver(MozbuildObject):
         buildstatus_messages=False,
         line_handler=None,
         append_env=None,
+        virtualenv_topobjdir=None,
     ):
         # Disable indexing in objdir because it is not necessary and can slow
         # down builds.
@@ -1660,11 +1663,12 @@ class BuildDriver(MozbuildObject):
                 if eq == "=":
                     append_env[k] = v
 
+        virtualenv_topobjdir = virtualenv_topobjdir or self.topobjdir
         build_site = CommandSiteManager.from_environment(
             self.topsrcdir,
             lambda: get_state_dir(specific_to_topsrcdir=True, topsrcdir=self.topsrcdir),
             "build",
-            os.path.join(self.topobjdir, "_virtualenvs"),
+            os.path.join(virtualenv_topobjdir, "_virtualenvs"),
         )
         build_site.ensure()