mercurial/help/common.txt

ui: edit(): rebase, graft: set HGREVISION environment variable for an editor

rebase and graft commands set 'rebase_source' or 'source' extras for the revision.
Allow an editor to access the extras using HGREVISION environment variable.

This may be useful when an editor is actually a script which modifies a commit
message.

The name 'HGREVISION' has been selected as transplant already sets this variable
for its filters (--filter).

.. 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