templatekw: make getrenamed() return only filename, not nodeid
No callers cared about the nodeid and I want to make getrenamed() not
look up the node (although it's currently free, I hope to store copy
info in changesets and not include the nodeid).
Differential Revision: https://phab.mercurial-scm.org/D3666
Test issue2761
$ hg init
$ touch to-be-deleted
$ hg add
adding to-be-deleted
$ hg ci -m first
$ echo a > to-be-deleted
$ hg ci -m second
$ rm to-be-deleted
$ hg diff -r 0
Same issue, different code path
$ hg up -C
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ touch does-not-exist-in-1
$ hg add
adding does-not-exist-in-1
$ hg ci -m third
$ rm does-not-exist-in-1
$ hg diff -r 1