tests/test-merge-subrepos.t

py3: replace os.pathsep with pycompat.ospathsep

os.pathsep returns unicode on Python 3. We already have pycompat.ospathsep
which return bytes on Python 3. This patch replaces all the occurrences of
os.pathsep in the codebase (excluding tests) to pycompat.ospathsep.

  $ hg init

  $ echo a > a
  $ hg ci -qAm 'add a'

  $ hg init subrepo
  $ echo 'subrepo = http://example.net/libfoo' > .hgsub
  $ hg ci -qAm 'added subrepo'

  $ hg up -qC 0
  $ echo ax > a
  $ hg ci -m 'changed a'
  created new head

  $ hg up -qC 1
  $ cd subrepo
  $ echo b > b
  $ hg add b
  $ cd ..

Should fail, since there are added files to subrepo:

  $ hg merge
  abort: uncommitted changes in subrepository 'subrepo'
  [255]