--- a/python/mozbuild/mozbuild/artifacts.py
+++ b/python/mozbuild/mozbuild/artifacts.py
@@ -413,25 +413,25 @@ class PushHeadCache(CacheManager):
                 '--template', '{node}\n',
                 '-r', 'last(pushhead("{tree}") and ::"{parent}", {num})'.format(
                     tree=tree, parent=parent, num=NUM_PUSHHEADS_TO_QUERY_PER_PARENT)])
             # Filter blank lines.
             pushheads = [ pushhead for pushhead in pushheads.strip().split('\n') if pushhead ]
             if pushheads:
                 return pushheads
         except subprocess.CalledProcessError as e:
-            # Probably don't have the mozext extension installed.
+            # We probably don't have the mozext extension installed.
             ret = subprocess.call([self._hg, 'showconfig', 'extensions.mozext'])
             if ret:
                 raise Exception('Could not find candidate pushheads.\n\n'
                                 'You need to enable the "mozext" hg extension: '
                                 'see https://developer.mozilla.org/en-US/docs/Artifact_builds')
             raise e
 
-        # Probably don't have the pushlog database present locally.  Check.
+        # We probably don't have the pushlog database present locally.  Check.
         tree_pushheads = subprocess.check_output([self._hg, 'log',
             '--template', '{node}\n',
             '-r', 'last(pushhead("{tree}"))'.format(tree=tree)])
         # Filter blank lines.
         tree_pushheads = [ pushhead for pushhead in tree_pushheads.strip().split('\n') if pushhead ]
         if tree_pushheads:
             # Okay, we have some pushheads but no candidates.  This can happen
             # for legitimate reasons: old revisions with no upstream builds