tests/test-issue619.t

test-walk: add more tests for -I/-X

We had very limited testing of -I and -X, especially when combined
with plain file patterns and with each other. This adds some more
protection against regressions as upcoming patches modify the matcher
code. (Originally meant for my own upcoming patches, but now I know
drgott will be sending some patches soon.)

The only noteworthy cases seems to be that both of

  hg debugwalk -Xbeans/black beans/black
  hg debugwalk -Xbeans beans/black

walk the file. I would personally have expected the -X to trump. I
don't care enough to change it, but I also think it's fair if some
future commit changes the behavior.

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]

Even with strange revset (issue4465)

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