histedit: use revset to check if we need to update during abort
The for loop is already quite more complicated than necessary and we are about
to add some logic. Instead, we use a simple revset. Revset laziness should
provide us with similar performance.
$ 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