revset: prefetch method in "parents"
As already demonstrated, saving attribute lookup gains us some minor but
noticeable performance improvements.
revset #0: parents(all())
before) 0.024169
after ) 0.022756 94%
#require symlink
http://mercurial.selenic.com/bts/issue1438
$ hg init
$ ln -s foo link
$ hg add link
$ hg ci -mbad link
$ hg rm link
$ hg ci -mok
$ hg diff -g -r 0:1 > bad.patch
$ hg up 0
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg import --no-commit bad.patch
applying bad.patch
$ hg status
R link
? bad.patch