hgweb: don't raise an exception when displying empty repos The nullid node claims it's in the default branch, but the branch dict is empty. This fixes the main symptom from issue696, but we may want to set branchtags()['default'] = nullid somewhere for empty repos.

#!/bin/sh

# Test for changeset ba7c74081861
# (update dirstate correctly for non-branchmerge updates)
hg init a
cd a
echo a > a
hg add a
hg commit -m a
cd ..
hg clone a b
cd a
hg mv a b
hg commit -m move
echo b >> b
hg commit -m b
cd ../b
hg pull ../a
hg update