template: add successors template
The successors templates display the closest visible successors of each
changeset, we may have gap, like in this case:
A -> B -> C -> D
If we display A, C and D but not B, we can't display than B is the closest
successor of A because it's not displayed. We display C as the closest
successor of A instead.
#require test-repo
$ checkflake8() {
> if ! (which flake8 > /dev/null); then
> echo skipped: missing tool: flake8;
> exit 80;
> fi;
> };
$ checkflake8
Copied from Mercurial core (60ee2593a270)
$ cd "`dirname "$TESTDIR"`"
run flake8 if it exists; if it doesn't, then just skip
$ hg files -0 'set:(**.py or grep("^#!.*python")) - removed()' 2>/dev/null \
> | xargs -0 flake8