posix: don't compare atime when determining if a file has changed
A file's atime might change even if the file itself doesn't change. This might
cause us to invalidate caches more often than necessary.
Before this change, hg add often resulted in the dirstate being parsed twice
on systems that track atime. After this change, it is only parsed once. For a
repository with over 180,000 files, this speeds up hg add from 1.2 seconds to
1.0.
http://mercurial.selenic.com/bts/issue612
$ hg init
$ mkdir src
$ echo a > src/a.c
$ hg ci -Ama
adding src/a.c
$ hg mv src source
moving src/a.c to source/a.c (glob)
$ hg ci -Ammove
$ hg co -C 0
1 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ echo new > src/a.c
$ echo compiled > src/a.o
$ hg ci -mupdate
created new head
$ hg status
? src/a.o
$ hg merge
merging src/a.c and source/a.c to source/a.c
0 files updated, 1 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ hg status
M source/a.c
R src/a.c
? src/a.o