doc/common.txt

histedit-test: ensure that non commute test will never commute

The previous version would commute if using merge algorithm (to be accurate,
merge will cleanly prompt the user during the merge).

The new version create and initial commit with some content for all involved
files en ensure all changes are a content changes of the first lines. This lead
to guaranteed conflict when commuted.

.. 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