doc/common.txt

tests: show skip reason instead of "irrelevant" with unified tests, too

parsehghaveoutput expects just the test output, not the merged test/output,
so for skipped unified tests e.g.:
Skipped test-convert-darcs.t: missing feature: irrelevant
was shown instead of:
Skipped test-convert-darcs.t: missing feature: darcs client

.. Common link and substitution definitions.

.. |hg(1)| replace:: **hg**\ (1)
.. _hg(1): hg.1.html
.. |hgrc(5)| replace:: **hgrc**\ (5)
.. _hgrc(5): hgrc.5.html
.. |hgignore(5)| replace:: **hgignore**\ (5)
.. _hgignore(5): hgignore.5.html