Fix logic error in gate-project-config-projects-yaml

Previously labels were only being checked for validity if an upstream
was given due to a premature 'continue' if no upstream is given before
checking labels.

Change-Id: I7dd564d59a30ca14bbad4044a985ba08fbe55ca5

tools/check_valid_gerrit_projects.py

@@ -60,8 +60,7 @@ for p in projects:
     # Allow git:// and https:// URLs for importing upstream repositories,
     # but not git@
     upstream = p.get('upstream')
-    if not upstream:
-        continue
+    if upstream:
         for prefix in VALID_SCHEMES:
             if upstream.startswith(prefix):
                 break