Bug 1824045 - Run pre-export/export steps in mach cargo even when configure has run. r=firefox-build-system-reviewers,ahochheiden

Differential Revision: https://phabricator.services.mozilla.com/D173373

python/mozbuild/mozbuild/mach_commands.py

@@ -236,11 +236,13 @@ def cargo(
     if cargo_extra_flags is not None:
         cargo_extra_flags = " ".join(cargo_extra_flags)
 
-    try:
-        command_context.config_environment
-    except BuildEnvironmentNotFoundException:
-        build = command_context._spawn(BuildDriver)
-        if cargo_build_flags:
+    ret = 0
+    if cargo_build_flags:
+        # This directory is created during export. If it's not there,
+        # export hasn't run already.
+        deps = Path(command_context.topobjdir) / ".deps"
+        if not deps.exists():
+            build = command_context._spawn(BuildDriver)
             ret = build.build(
                 command_context.metrics,
                 what=["pre-export", "export"],
@@ -248,13 +250,17 @@ def cargo(
                 verbose=verbose,
                 mach_context=command_context._mach_context,
             )
-        else:
+    else:
+        try:
+            command_context.config_environment
+        except BuildEnvironmentNotFoundException:
+            build = command_context._spawn(BuildDriver)
             ret = build.configure(
                 command_context.metrics,
                 buildstatus_messages=False,
             )
-        if ret != 0:
-            return ret
+    if ret != 0:
+        return ret
 
     # XXX duplication with `mach vendor rust`
     crates_and_roots = {