tests/test-sparse-clear.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'
    ]

test sparse

  $ hg init myrepo
  $ cd myrepo
  $ cat >> $HGRCPATH <<EOF
  > [extensions]
  > sparse=
  > purge=
  > strip=
  > rebase=
  > EOF

  $ echo a > index.html
  $ echo x > data.py
  $ echo z > readme.txt
  $ cat > base.sparse <<EOF
  > [include]
  > *.sparse
  > EOF
  $ hg ci -Aqm 'initial'
  $ cat > webpage.sparse <<EOF
  > %include base.sparse
  > [include]
  > *.html
  > EOF
  $ hg ci -Aqm 'initial'

Clear rules when there are includes

  $ hg debugsparse --include *.py
  $ ls -A
  .hg
  data.py
  $ hg debugsparse --clear-rules
  $ ls -A
  .hg
  base.sparse
  data.py
  index.html
  readme.txt
  webpage.sparse

Clear rules when there are excludes

  $ hg debugsparse -X base.sparse -X webpage.sparse
  $ ls -A
  .hg
  data.py
  index.html
  readme.txt
  $ hg debugsparse --clear-rules
  $ ls -A
  .hg
  base.sparse
  data.py
  index.html
  readme.txt
  webpage.sparse

Clearing rules should not alter profiles

  $ hg debugsparse --enable-profile webpage.sparse
  $ ls -A
  .hg
  base.sparse
  index.html
  webpage.sparse
  $ hg debugsparse --include *.py
  $ ls -A
  .hg
  base.sparse
  data.py
  index.html
  webpage.sparse
  $ hg debugsparse --clear-rules
  $ ls -A
  .hg
  base.sparse
  index.html
  webpage.sparse