tests/test-eol-tag.t

run-tests: fix conditional when tests are run outside of `tests`

The logic to find `hghave` was using `__file__` but… non absolute path in
`__file__` gets wrong as soon as we change directory (thanks python… you are
being helpful). The rest of the `run-tests.py` code already deal with this
fine. We simply reuse the `RUNTESTDIR` variable to fix it.

https://bz.mercurial-scm.org/2493

Testing tagging with the EOL extension

  $ cat >> $HGRCPATH <<EOF
  > [extensions]
  > eol =
  > 
  > [eol]
  > native = CRLF
  > EOF

setup repository

  $ hg init repo
  $ cd repo
  $ cat > .hgeol <<EOF
  > [patterns]
  > ** = native
  > EOF
  $ printf "first\r\nsecond\r\nthird\r\n" > a.txt
  $ hg commit --addremove -m 'checkin'
  adding .hgeol
  adding a.txt

Tag:

  $ hg tag 1.0

Rewrite .hgtags file as it would look on a new checkout:

  $ hg update -q null
  $ hg update -q

Touch .hgtags file again:

  $ hg tag 2.0

  $ cd ..