Sync engine: Restart sync when we get a precondition failed error

src/mirall/propagator_qnam.cpp

@@ -310,6 +310,7 @@ void PropagateUploadFileQNAM::slotPutFinished()
             // Precondition Failed:   Maybe the bad etag is in the database, we need to clear the
             // parent folder etag so we won't read from DB next sync.
             _propagator->_journal->avoidReadFromDbOnNextSync(_item._file);
+            _propagator->_anotherSyncNeeded = true;
         }
 
         done(classifyError(err, _item._httpErrorCode), errorString);