code: private void unshallowIfNeeded(GitCommand gitCommand, ConsoleOutputStreamConsumer streamConsumer, Revision revision, File workingDir) {
          if (gitCommand.isShallow() && !gitCommand.containsRevisionInBranch(revision)) {
              gitCommand.unshallow(streamConsumer, UNSHALLOW_TRYOUT_STEP);
  
              if (gitCommand.isShallow() && !gitCommand.containsRevisionInBranch(revision)) {
                  fullyUnshallow(gitCommand, streamConsumer);
              }
          }
      }
docs: unshallow the whole repo with "git fetch --2147483647".