Bug 1628498 - Hackaround: Try to build virtualenv from scratch if there was a previous one. r=rstewart

This works for me and should allow trees to reopen.

Differential Revision: https://phabricator.services.mozilla.com/D70415

--HG--
extra : histedit_source : 529e1cb5cdb3030f145f44fc1ebf0ea9ae00aa8f

python/mozbuild/mozbuild/virtualenv.py

@@ -222,6 +222,7 @@ class VirtualenvManager(object):
         called out to), the path to create the virtualenv in, and a handle to
         write output to.
         """
+        existed = os.path.exists(self.virtualenv_root)
 
         args = [python, self.virtualenv_script_path,
                 # Without this, virtualenv.py may attempt to contact the outside
@@ -233,6 +234,11 @@ class VirtualenvManager(object):
 
         result = self._log_process_output(args)
 
+        if result and existed:
+            # Try again after removing the previous env, see bug 1628644.
+            shutil.rmtree(self.virtualenv_root)
+            result = self._log_process_output(args)
+
         if result:
             raise Exception(
                 'Failed to create virtualenv: %s (virtualenv.py retcode: %s)' % (