cmdutil: changeset_printer: use methods of filectx/changectx.
This allows extensions that modify changeset metadata (e.g.
description) by overriding methods of changectx to get consistent
behavior from all log-like commands, regardless of whether templates
or styles are used. Without this, overriding changectx methods works
if you use styles or templates, but not with default log format.
This meant adding filectx.extra() for consistency with changectx.
#!/bin/sh
# In the merge below, the file "foo" has the same contents in both
# parents, but if we look at the file-level history, we'll notice that
# the version in p1 is an ancestor of the version in p2. This test
# makes sure that we'll use the version from p2 in the manifest of the
# merge revision.
hg init repo
cd repo
echo foo > foo
hg ci -qAm 'add foo'
echo bar >> foo
hg ci -m 'change foo'
hg backout -r tip -m 'backout changed foo'
hg up -C 0
touch bar
hg ci -qAm 'add bar'
hg merge --debug
hg debugstate | grep foo
hg st -A foo
hg ci -m 'merge'
hg manifest --debug | grep foo
hg debugindex .hg/store/data/foo.i