rhg: desambiguate status without decompressing filelog if possible
When status is unsure based on `stat()` and the dirstate if a file is clean
or modified, we need to compare it against the filelog.
This comparison can skip looking at contents if the lengths differ.
This changeset optimize this further to deduce what we can about the length
if the filelog without decompressing it or resolving deltas.
Differential Revision: https://phab.mercurial-scm.org/D11965
https://bz.mercurial-scm.org/612
$ 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
$ 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