annotate: reuse already calculated annotation
Before this patch, annotation is re-calculated even if it is already
calculated. This may cause unexpected annotation, because already
cleared "pcache" ("pcache[f] = []") prevents from scanning ancestors.
This patch reuses already calculated annotation if it is available.
In fact, "reusable" situation should be seen only on legacy
repositories in which a filelog include the merging between the
revision and its ancestor, because:
- tree is scanned in depth-first
without such merging, annotation result should be released soon
- recent Mercurial doesn't allow such merging
changelog and manifest can include such merging someway, but
filelogs can't, because "localrepository._filecommit()" converts
such merging request to linear history.
$ hg init
$ echo a > a
$ hg ci -Am t
adding a
$ hg mv a b
$ hg ci -Am t1
$ hg debugrename b
b renamed from a:b789fdd96dc2f3bd229c1dd8eedf0fc60e2b68e3
$ hg mv b a
$ hg ci -Am t2
$ hg debugrename a
a renamed from b:37d9b5d994eab34eda9c16b195ace52c7b129980
$ hg debugrename --rev 1 b
b renamed from a:b789fdd96dc2f3bd229c1dd8eedf0fc60e2b68e3