Bug 1717051: Automatically create and activate Mach virtualenv r=ahal

Consolidate Mach virtualenv management to the front of the
Mach process. This obsoletes `./mach create-mach-environment`
and simplifies the `sh` portion of the top-level `./mach` script.

This helps ensure that the Mach virtualenv doesn't become
out-of-sync and simplifies the mental model of the Mach
virtualenv situation.

Differential Revision: https://phabricator.services.mozilla.com/D120401

build/mach_initialize.py

@@ -179,38 +179,14 @@ def _activate_python_environment(topsrcdir, state_dir):
         )
     ]
 
-    from mach.site import (
-        MachSiteManager,
-        VirtualenvOutOfDateException,
-        MozSiteMetadata,
-        MozSiteMetadataOutOfDateError,
-    )
+    from mach.site import MachSiteManager
 
-    try:
-        active_metadata = MozSiteMetadata.from_runtime()
-        if not active_metadata and os.path.basename(sys.prefix) == "mach":
-            # Until the new "MozVirtualenvMetadata" code has been live for long enough,
-            # there will be Mach virtualenvs without associated "metadata" files.
-            # Since "active_metadata" will be "None" in these cases, let's try
-            # to identify them with a dumb, but mostly correct, "parent directory name"
-            # check.
-            # If the check matches, then the virtualenv should be re-generated so it
-            # gets its metadata file.
-            raise MozSiteMetadataOutOfDateError(
-                "Mach virtualenv is missing metadata file."
-            )
-        mach_environment = MachSiteManager.from_environment(
-            topsrcdir,
-            # normpath state_dir to normalize msys-style slashes.
-            os.path.normpath(state_dir),
-        )
-        mach_environment.activate()
-    except (VirtualenvOutOfDateException, MozSiteMetadataOutOfDateError):
-        print(
-            'The "mach" virtualenv is not up-to-date, please run '
-            '"./mach create-mach-environment"'
-        )
-        sys.exit(1)
+    mach_environment = MachSiteManager.from_environment(
+        topsrcdir,
+        # normpath state_dir to normalize msys-style slashes.
+        os.path.normpath(state_dir),
+    )
+    mach_environment.activate()
 
 
 def initialize(topsrcdir):
@@ -430,8 +406,8 @@ def _finalize_telemetry_glean(telemetry, is_bootstrap, success):
 
     has_psutil, logical_cores, physical_cores, memory_total = get_psutil_stats()
     if has_psutil:
-        # psutil may not be available (we allow `mach create-mach-environment`
-        # to fail to install it).
+        # psutil may not be available (we may not have been able to download
+        # a wheel or build it from source).
         system_metrics.logical_cores.add(logical_cores)
         system_metrics.physical_cores.add(physical_cores)
         if memory_total is not None: