view CONTRIBUTING @ 35489:1721ce06100a

hgweb: display fate of obsolete changesets

Operations that obsolete changesets store enough metadata to explain what
happened after the fact. One way to get that metadata is showsuccsandmarkers
function, which returns a list of successors of a particular changeset and
appropriate obsolescence markers.

Templates have a set of experimental functions that have names starting with
obsfate. This patch uses some of these functions to interpret output of
succsandmarkers() and produce human-friendly messages that describe what
happened to an obsolete changeset, e.g. "pruned" or "rewritten as
6:3de5eca88c00".

In commonentry(), succsandmarkers property is made callable so it's only
executed on demand; this saves time when changeset is not obsolete, and also in
e.g. /shortlog view, where there are a lot of changesets, but we don't need to
show each and every one in detail.

In spartan theme, succsandmarkers is used instead of the simple "obsolete:
yes", in other themes a new line is added to /rev page.

Our full contribution guidelines are in our wiki, please see:

https://www.mercurial-scm.org/wiki/ContributingChanges

If you just want a checklist to follow, you can go straight to

https://www.mercurial-scm.org/wiki/ContributingChanges#Submission_checklist

If you can't run the entire testsuite for some reason (it can be
difficult on Windows), please at least run `contrib/check-code.py` on
any files you've modified and run `python contrib/check-commit` on any
commits you've made (for example, `python contrib/check-commit
273ce12ad8f1` will report some style violations on a very old commit).