tests/test-issue619.t

mq: report correct numbers for changing "number of guarded, applied patches"

Before this patch, "hg qselect" may report incorrect numbers for
"number of guarded, applied patches has changed", because it examines
"pushable" of patches by the index not in "the series" but in "applied
patches", even though "mq.pushable()" expects the former.

To report correct numbers for changing "number of guarded, applied
patches", this patch uses the name of applied patch to examine
pushable-ness of it.

This patch also changes the result of existing "hg qselect" tests,
because they doesn't change pushable-ness of already applied patches.

This patch assumes that "hg qselect" focuses on changing pushable-ness
only of already applied patches, because:

  - the report message uses not "previous" (in the series) but
    "applied"

  - the logic to pop patches for --pop/--reapply examines
    pushable-ness only of already applied ones (in fact, there are
    some incorrect code paths)

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]