tests/test-fix-clang-format.t

run-tests: stop ignoring venv-installed packages

This will allow test dependencies to be installed within a venv, instead of
tampering with sys/user sites.  One thing to note here is that the `VIRTUAL_ENV`
path takes precedence over system-site, unlike when run directly with an
activated `venv`.  For example, `sys.path` as viewed from a feature test in
`hghave.py`, when running `hghave vcr` directly with an activated `venv`:

    sys.path: [
        '/home/jenkins/hg-committed/tests',
        '/usr/lib/python38.zip',
        '/usr/lib/python3.8',
        '/usr/lib/python3.8/lib-dynload',
        '/home/jenkins/test_venv/lib/python3.8/site-packages'
    ]

vs `sys.path` from the same feature test, when run by `run-tests.py` with this
change:

    sys.path: [
        '/home/jenkins/hg-committed/tests',
        '/home/jenkins/hg-committed',
        '/home/jenkins/hg-committed/tests',
        '/home/jenkins/test_venv/lib/python3.8/site-packages',
        '/usr/lib/python38.zip',
        '/usr/lib/python3.8',
        '/usr/lib/python3.8/lib-dynload',
        '/home/jenkins/.local/lib/python3.8/site-packages',
        '/usr/local/lib/python3.8/dist-packages',
        '/usr/lib/python3/dist-packages'
    ]

#require clang-format

Test that a simple "hg fix" configuration for clang-format works.

  $ cat >> $HGRCPATH <<EOF
  > [extensions]
  > fix =
  > [experimental]
  > evolution.createmarkers=True
  > evolution.allowunstable=True
  > [fix]
  > clang-format:command=clang-format --style=Google --assume-filename={rootpath}
  > clang-format:linerange=--lines={first}:{last}
  > clang-format:pattern=set:**.cpp or **.hpp
  > EOF

  $ hg init repo
  $ cd repo

  $ printf "void foo(){int x=2;}\n" > foo.cpp
  $ printf "void\nfoo();\n" > foo.hpp
  $ hg commit -Am "foo commit"
  adding foo.cpp
  adding foo.hpp
  $ hg cat -r tip *
  void foo(){int x=2;}
  void
  foo();
  $ hg fix -r tip
  $ hg cat -r tip *
  void foo() { int x = 2; }
  void foo();

  $ cd ..