evolve: fix use of "'%d' % ctx"
ctx has not been convertible to int since Mercurial commit
38f480502043 (context: remove basectx.__int__ (API), 2018-02-24). I
decided to use "%s" instead to match other similar messages in
evolvecmd.py. I also added a space to match the other messages.
#require test-repo pyflakes
Copied from Mercurial core (60ee2593a270)
$ cd "`dirname "$TESTDIR"`"
run pyflakes on all tracked files ending in .py or without a file ending
(skipping binary file random-seed)
$ hg locate 'set:(**.py or grep("^#!.*python")) - removed()' 2>/dev/null \
> | xargs pyflakes 2>/dev/null