tests/blacklists/fsmonitor

run-tests: handle json.dumps divergence

In py2, json.dumps includes a trailing space after a comma at the
end of lines. The py3 behavior which omits the trailing space is
preferable, so we're going to strip it.

# Blacklist for a full testsuite run with fsmonitor enabled.
# Use with
#     run-tests --blacklist=blacklists/fsmonitor \
#         --extra-config="extensions.fsmonitor="
# The following tests all fail because they either use extensions that conflict
# with fsmonitor, use subrepositories, or don't anticipate the extra file in
# the .hg directory that fsmonitor adds.
test-basic.t
test-blackbox.t
test-check-commit.t
test-commandserver.t
test-copy.t
test-debugextensions.t
test-eol-add.t
test-eol-clone.t
test-eol-hook.t
test-eol-patch.t
test-eol-tag.t
test-eol-update.t
test-eol.t
test-eolfilename.t
test-extension.t
test-fncache.t
test-hardlinks.t
test-help.t
test-inherit-mode.t
test-issue3084.t
test-largefiles-cache.t
test-largefiles-misc.t
test-largefiles-small-disk.t
test-largefiles-update.t
test-largefiles-wireproto.t
test-largefiles.t
test-lfconvert.t
test-merge-tools.t
test-nested-repo.t
test-permissions.t
test-push-warn.t
test-subrepo-deep-nested-change.t
test-subrepo-recursion.t
test-subrepo.t
test-tags.t

# The following tests remain enabled; they fail *too*, but only because they
# occasionally use blacklisted extensions and don't anticipate the warning
# generated.
#test-log.t
#test-hook.t
#test-rename.t
#test-histedit-fold.t
#test-fileset-generated.t
#test-init.t