tests/test-check-execute.t

py3: replace file() with open() in test-convert-mtn.t

While I was here, I added b'' prefixes to make sure we write things correctly in
bytes mode on Python 3.

Differential Revision: https://phab.mercurial-scm.org/D2111

#require test-repo execbit

  $ . "$TESTDIR/helpers-testrepo.sh"
  $ cd "`dirname "$TESTDIR"`"

look for python scripts without the execute bit

  $ testrepohg files 'set:**.py and not exec() and grep(r"^#!.*?python")'
  [1]

look for python scripts with execute bit but not shebang

  $ testrepohg files 'set:**.py and exec() and not grep(r"^#!.*?python")'
  [1]

look for shell scripts with execute bit but not shebang

  $ testrepohg files 'set:**.sh and exec() and not grep(r"^#!.*(ba)?sh")'
  [1]

look for non scripts with no shebang

  $ testrepohg files 'set:exec() and not **.sh and not **.py and not grep(r"^#!")'
  [1]