Jun Wu <quark@fb.com> [Fri, 11 Aug 2017 01:08:07 -0700] rev 33849
rebase: optimize "source" calculation in adjustdest
The "source" variable is calculated inside a loop but it does not depend on
loop variables. Therefore move it outside the loop.
Differential Revision: https://phab.mercurial-scm.org/D345