tests: verify that Python scripts are blackened

Scripts are Python too. They should be blackened.

(As suggested by Pierre-Yves in D7420.)

Differential Revision: https://phab.mercurial-scm.org/D7447

tests/test-check-format.t

@@ -1,5 +1,5 b''
 #require black
 
   $ cd $RUNTESTDIR/..
-  $ black --config=black.toml --check --diff `hg files 'set:**.py - mercurial/thirdparty/** - "contrib/python-zstandard/**"'`
+  $ black --config=black.toml --check --diff `hg files 'set:(**.py + grep("^#!.*python")) - mercurial/thirdparty/** - "contrib/python-zstandard/**"'`
 

tests/test-check-shbang.t

@@ -1,25 +1,26 b''
 #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
   [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]