Emit project info in case of sync exception.

Previously repo would only print the failing project path if
Sync_NetworkHalf returned false/empty, but if it threw an
exception the print() was never called.

Change-Id: I58c41de43930df5e34b21561c205e062a72e290f

subcmds/sync.py

@@ -292,7 +292,9 @@ later is required to fix a server side protocol bug.
         pm.update()
       except _FetchError:
         err_event.set()
-      except:
+      except Exception as e:
+        print('error: Cannot fetch %s (%s: %s)' \
+            % (project.name, type(e).__name__, str(e)), file=sys.stderr)
         err_event.set()
         raise
     finally: