Store empty (default) branch in branch cache, too.
Operations on this branch don't work otherwise.
Reading branches.cache had to be adjusted to allow an empty label.
Adjusted reading of the cache tip for symmetry, no functional change here.
#!/bin/sh
cat <<EOF >> $HGRCPATH
[extensions]
notify=
[hooks]
incoming.notify = python:hgext.notify.hook
[notify]
sources = pull
diffstat = False
[usersubs]
foo@bar = *
[reposubs]
* = baz
EOF
hg help notify
hg init a
echo a > a/a
echo % commit
hg --traceback --cwd a commit -Ama -d '0 0'
echo % clone
hg --traceback clone a b
echo a >> a/a
echo % commit
hg --traceback --cwd a commit -Amb -d '1 0'
echo '% pull (minimal config)'
hg --traceback --cwd b pull ../a 2>&1 | sed -e 's/\(Message-Id:\).*/\1/' \
-e 's/changeset \([0-9a-f]* *\)in .*test-notif/changeset \1in test-notif/' \
-e 's/^details: .*test-notify/details: test-notify/'
cat <<EOF >> $HGRCPATH
[notify]
config = $HGTMP/.notify.conf
domain = test.com
strip = 3
template = Subject: {desc|firstline|strip}\nFrom: {author}\n\nchangeset {node|short} in {webroot}\ndescription:\n\t{desc|tabindent|strip}
[web]
baseurl = http://test/
EOF
echo % pull
hg --cwd b rollback
hg --traceback --cwd b pull ../a 2>&1 | sed -e 's/\(Message-Id:\).*/\1/' \
-e 's/changeset \([0-9a-f]*\) in .*/changeset \1/'