changegroup: refactor emitrevision to use a `deltamode` argument
This new argument gathers the semantic of `sendfulltext` and `deltaprevious`
in a single value. We are about to introduce a new type of constraints.
Avoiding yet another argument sounds like a plus.
#require docutils gettext
Error: the current ro localization has some rst defects exposed by
moving pager to core. These two warnings about references are expected
until the localization is corrected.
$ $TESTDIR/check-gendoc ro
checking for parse errors
gendoc.txt:58: (WARNING/2) Inline interpreted text or phrase reference start-string without end-string.
gendoc.txt:58: (WARNING/2) Inline interpreted text or phrase reference start-string without end-string.