tests/test-empty-dir.t

doc: unify help text for "--edit" option

This patch changes help text for "--edit" option of commands below:

  - fetch
  - qnew
  - qrefresh
  - qfold
  - commit
  - tag

This unification reduces translation cost, too.

This patch chooses not "further edit commit message already specified"
(of "hg commit") but "invoke editor on commit messages" as unified
help text for "--edit" option, because the latter is much older than
the former.

  $ hg init

  $ echo 123 > a
  $ hg add a
  $ hg commit -m "first" a

  $ mkdir sub
  $ echo 321 > sub/b
  $ hg add sub/b
  $ hg commit -m "second" sub/b

  $ cat sub/b
  321

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

  $ cat sub/b 2>/dev/null || echo "sub/b not present"
  sub/b not present

  $ test -d sub || echo "sub not present"
  sub not present