Bug 1746325: Defer/avoid creation of scoped state dir for command sites r=ahal

In CI, we sometimes don't have permissions to create a scoped state dir.
Additionally, the current behaviour for resolving the path to a scoped
state dir will also attempt to create it if it doesn't exist.

There's likely a more eloquent solution, but the short-term fix is to
have sites defer the resolution of the state dir until they _know_ they
need it.

Differential Revision: https://phabricator.services.mozilla.com/D134066

python/mach/mach/site.py

@@ -228,7 +228,7 @@ class MachSiteManager:
         """
         Args:
             topsrcdir: The path to the Firefox repo
-            get_state_dir: A function that resolve the path to the checkout-scoped
+            get_state_dir: A function that resolves the path to the checkout-scoped
                 state_dir, generally ~/.mozbuild/srcdirs/<checkout-based-dir>/
         """
 
@@ -440,15 +440,15 @@ class CommandSiteManager:
     def from_environment(
         cls,
         topsrcdir: str,
-        checkout_scoped_state_dir: Optional[str],
+        get_state_dir: Callable[[], Optional[str]],
         site_name: str,
         command_virtualenvs_dir: str,
     ):
         """
         Args:
             topsrcdir: The path to the Firefox repo
-            checkout_scoped_state_dir: The path to the checkout-scoped state_dir,
-                generally ~/.mozbuild/srcdirs/<checkout-based-dir>/
+            get_state_dir: A function that resolves the path to the checkout-scoped
+                state_dir, generally ~/.mozbuild/srcdirs/<checkout-based-dir>/
             site_name: The name of this site, such as "build"
             command_virtualenvs_dir: The location under which this site's virtualenv
             should be created
@@ -479,6 +479,12 @@ class CommandSiteManager:
                 else SitePackagesSource.NONE
             )
 
+        checkout_scoped_state_dir = (
+            get_state_dir()
+            if active_metadata.mach_site_packages_source == SitePackagesSource.VENV
+            else None
+        )
+
         return cls(
             topsrcdir,
             checkout_scoped_state_dir,

python/mozbuild/mozbuild/base.py

@@ -295,7 +295,9 @@ class MozbuildObject(ProcessExecutionMixin):
         if self._virtualenv_manager is None:
             self._virtualenv_manager = CommandSiteManager.from_environment(
                 self.topsrcdir,
-                get_state_dir(specific_to_topsrcdir=True, topsrcdir=self.topsrcdir),
+                lambda: get_state_dir(
+                    specific_to_topsrcdir=True, topsrcdir=self.topsrcdir
+                ),
                 self._virtualenv_name,
                 os.path.join(self.topobjdir, "_virtualenvs"),
             )

python/mozbuild/mozbuild/controller/building.py

@@ -1661,7 +1661,7 @@ class BuildDriver(MozbuildObject):
 
         build_site = CommandSiteManager.from_environment(
             self.topsrcdir,
-            get_state_dir(specific_to_topsrcdir=True, topsrcdir=self.topsrcdir),
+            lambda: get_state_dir(specific_to_topsrcdir=True, topsrcdir=self.topsrcdir),
             "build",
             os.path.join(self.topobjdir, "_virtualenvs"),
         )

python/mozbuild/mozbuild/sphinx.py

@@ -217,7 +217,7 @@ def setup(app):
     topsrcdir = manager.topsrcdir
     site = CommandSiteManager.from_environment(
         topsrcdir,
-        get_state_dir(specific_to_topsrcdir=True, topsrcdir=topsrcdir),
+        lambda: get_state_dir(specific_to_topsrcdir=True, topsrcdir=topsrcdir),
         "common",
         os.path.join(app.outdir, "_venv"),
     )