tests/test-issue619.t

windows: use normalized path as path to subrepo

path to subrepo is used to identify or check location of subrepo.

it should be normalized (in "/" delimiter form), because it is also
used with narrowmatcher which uses only normalized path even on
Windows environment.

this patch applies "util.pconvert()" on path to subrepo (called
"subpath") to normalize it.

for this patch, referers of below were checked.

  - subrepo.state()
  - subrepo.itersubrepos()
  - subrepo.subrepo()
  - context.sub()
  - context.substate()

typical usecase is:

    for subpath in ctx.substate:
        sub = ctx.sub(subpath)
        ... ctx.substate[subpath] ....

in this case, normalization has no side effect, because keys given
from substate are used as key itself.

other cases shown below also seem to require subpath to be normalized.

    - path components are joined by "/", in "commands.forget()":

        for subpath in ctx.substate:
            subforget[subpath + '/' + fsub] = (fsub, sub)

    - normalized "file" is used to check below condition, in
      "commands.revert()", "localrepository.commit()", and
      "localrepository._checknested()"

        file in ctx.substate

    - substate.keys() is passed to dirstate.walk()/status() which use
      only normalized pathes

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]