tests/test-issue1102.t

tests: proof test-stdio.py against buffer fill-up

With the previous code, it could in theory happen that the pipe / PTY buffer of
the child stdout / stderr fills up and the process never finishes.

To prevent that, we read all of the stream before waiting for the end of the
process. To ensure that the stream reaches EOF when the child finishes, we must
close the parent "copy" of the child stdout / stderr.

  $ rm -rf a
  $ hg init a
  $ cd a
  $ echo a > a
  $ hg ci -Am0
  adding a
  $ hg tag t1 # 1
  $ hg tag --remove t1 # 2

  $ hg co 1
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg tag -f -r0 t1
  $ hg tags
  tip                                3:a49829c4fc11
  t1                                 0:f7b1eb17ad24

  $ cd ..