Also find correct column width of wide characters.
Use unicodedata.east_asian_width() to determine wide/full width
characters if available. Otherwise, return character count as before.
% init repo1
% add a; ci
adding a
% cat .hg/store/fncache
data/a.i
% add a.i/b; ci
adding a.i/b
% cat .hg/store/fncache
data/a.i
data/a.i.hg/b.i
% add a.i.hg/c; ci
adding a.i.hg/c
% cat .hg/store/fncache
data/a.i
data/a.i.hg/b.i
data/a.i.hg.hg/c.i
% hg verify
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
3 files, 3 changesets, 3 total revisions
% rm .hg/store/fncache
% hg verify
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
data/a.i@0: missing revlog!
data/a.i.hg.hg/c.i@0: missing revlog!
data/a.i.hg/b.i@0: missing revlog!
3 files, 3 changesets, 3 total revisions
3 integrity errors encountered!
(first damaged changeset appears to be 0)