templatekw: make {successorssets} always return a list (issue6342)
Previously, {successorssets} returns an empty string instead of an empty list
for a non-obsolete changeset. The changing type of the JSON output makes it
hard to consume from statically-typed languages.
Differential Revision: https://phab.mercurial-scm.org/D9158
$ hg init
$ echo a > a
$ hg ci -Ama
adding a
$ hg an a
0: a
$ hg --config ui.strict=False an a
0: a
$ echo "[ui]" >> $HGRCPATH
$ echo "strict=True" >> $HGRCPATH
$ hg an a
hg: unknown command 'an'
(use 'hg help' for a list of commands)
[255]
$ hg annotate a
0: a
should succeed - up is an alias, not an abbreviation
$ hg up
0 files updated, 0 files merged, 0 files removed, 0 files unresolved