convert: Using --dest-type svn crashed, if the source repo used tags.
The convert extension requires puttags(self, tags) to return a sequence
for a multi-variable assignment. If puttags implicitly returns None,
the code will break when trying to un-pack None for assignment.
#!/bin/sh
hg init test
cd test
echo foo > a
hg ci -Ama
hg up -r0000
echo bar > a
echo % should issue warning
hg ci -Amb
hg up -r0000
echo stuffy > a
echo % should not issue warning
hg ci -q -Amc
hg up -r0000
echo crap > a
hg branch testing
echo % should not issue warning
hg ci -q -Amd