In 'Tips for jQuery Bug Patching',run following

$ git clone git@github.com:username/jquery.git

$ grunt && grunt watch

the "update_submodules" task failded with

fatal: Needed a single revision

Unable to find current revision in submodule path 'src/sizzle'

and when clone with

git clone --recursive git@github.com:xing-kenny/jquery.git

there are some Submodule clone info more than

git clone git@github.com:xing-kenny/jquery.git

Is there should add '--recursive' ?