context: delete mistaken comment about return value of renamed()
The comment seems to think that the return value of renamed() is a
tuple of source pathsx in the parents, but it's actually a pair of
(rename source path, file nodeid).
Differential Revision: https://phab.mercurial-scm.org/D5639
$ hg init
$ echo This is file a1 > a
$ hg add a
$ hg commit -m "commit #0"
$ ls
a
$ echo This is file b1 > b
$ hg add b
$ hg commit -m "commit #1"
$ hg co 0
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
B should disappear
$ ls
a