simplemerge: take arguments as annotated context objects
The labels we put in conflict markers are formatted so the part before
the ':' (typically says things like "local") is padded so the ':' is
aligned among the labels. That means that if you specify a long label
for "base" but the conflict marker style is "merge" (i.e. 2-way), the
other two will have unwanted padding. We often don't specify a label
for the base, so we don't notice the problem (and it may very well be
that it didn't exist before my D11972).
I think the best fix is to pass the labels along with the context
objects, so the low-level code that switches on the marker style to
use (i.e. `simplemerge`) can do the formatting. This patch starts
doing that by passing a fully-formatted label to `simplemerge`. A
coming patch will move the formatting to `simplemerge`.
Differential Revision: https://phab.mercurial-scm.org/D12013
#require docutils gettext
$ $TESTDIR/check-gendoc de
checking for parse errors
Die Dateien werden dem Projektarchiv beim n\xc3\xa4chsten \xc3\x9cbernehmen (commit) hinzugef\xc3\xbcgt. Um dies vorher r\xc3\xbcckg\xc3\xa4ngig zu machen, siehe:hg:`forget`. (esc)
warning: please have a space before :hg: