tests/test-issue619.t

dirstate: avoid normalizing letter case on icasefs for exact match (issue3340)

on icasefs, "hg qnew" fails to import changing letter case of filename
already occurred in working directory, for example:

    $ hg rename a tmp
    $ hg rename tmp A
    $ hg qnew casechange
    $ hg status
    R a
    $

"hg qnew" invokes 'dirstate.walk()' via 'localrepository.commit()'
with 'exact match' matching object having exact filenames of targets
in ones 'files()'.

current implementation of 'dirstate.walk()' always normalizes letter
case of filenames from 'match.files()' on icasefs, even though exact
matching is required.

then, files only different in letter case are treated as one file.

this patch prevents 'dirstate.walk()' from normalizing, if exact
matching is required, even on icasefs.

filenames for 'exact matching' are given not from user command line,
but from dirstate walk result, manifest of changecontext, patch files
or fixed list for specific system files (e.g.: '.hgtags').

in such case, case normalization should not be done, so this patch
works well.

http://mercurial.selenic.com/bts/issue619

  $ hg init
  $ echo a > a
  $ hg ci -Ama
  adding a

  $ echo b > b
  $ hg branch b
  marked working directory as branch b
  (branches are permanent and global, did you want a bookmark?)
  $ hg ci -Amb
  adding b

  $ hg co -C 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved

Fast-forward:

  $ hg merge b
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ hg ci -Ammerge

Bogus fast-forward should fail:

  $ hg merge b
  abort: merging with a working directory ancestor has no effect
  [255]