Comment 72 for bug 1672297

Yes, many Ubuntu packages are customized and often don't work unless you use the same customization options in your build. You can find out what those are by running 'apt-get source FOO' and then looking in debian/rules. However it's too complicated to write a clear guide for.

Also, it sounds like you may be building the wrong project. The leak is in project 'gjs', not 'gnome-shell'.