tests/test-check-shbang.t

tests: force `dummysmtpd.py` to write its log file with '\n' on Windows

The log files were being `cat'd` in `test-patchbomb-tls.t`, and causing
gratuitous failures.  Since `sys.stdout` is being written to with `str` instead
of `bytes`, use a `io.TextIOWrapper` to change the EOL, like 2924676d4728.

#require test-repo

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

look for python scripts that do not use /usr/bin/env

  $ testrepohg files 'set:grep(r"^#!.*?python") and not grep(r"^#!/usr/bi{1}n/env python") - **/*.t'
  [1]

In tests, enforce $PYTHON and *not* /usr/bin/env python or similar:
  $ testrepohg files 'set:grep(r"#!.*?python") and **/*.t' \
  > -X tests/test-check-execute.t \
  > -X tests/test-check-format.t \
  > -X tests/test-check-module-imports.t \
  > -X tests/test-check-pyflakes.t \
  > -X tests/test-check-shbang.t \
  > -X tests/test-highlight.t
  [1]

The above exclusions are because they're looking for files that
contain Python but don't end in .py - please avoid adding more.

look for shell scripts that do not use /bin/sh

  $ testrepohg files 'set:grep(r"^#!.*/bi{1}n/sh") and not grep(r"^#!/bi{1}n/sh")'
  [1]