update.py: fix regression handling layers that failed to fetch

If the layer failed to fetch, we shouldn't be attempting to update its
contents. (This got broken when we split the update script into two in
c64e4c57a9).

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>

layerindex/update.py

@@ -175,6 +175,7 @@ def main():
             for layer in layerquery:
                 if layer.vcs_url in failedrepos:
                     logger.info("Skipping update of layer %s as fetch of repository %s failed" % (layer.name, layer.vcs_url))
+                    continue
 
                 urldir = layer.get_fetch_dir()
                 repodir = os.path.join(fetchdir, urldir)