bundle2: add 'source' atrribute to bundleoperation class
This will help us in easily finding out which command leads to the current
operation without hacking on the transaction.
Differential Revision: https://phab.mercurial-scm.org/D2993
infinitepush: don't force ipv6 while connecting to mysql server
Facebook internally enforces this but looks like we can't force this for pur
users.
Differential Revision: https://phab.mercurial-scm.org/D2992