mq: preserve --git flag when folding patches
Without this, folding a git patch into a regular one downgrades the resulting
patch to a regular patch.
#!/bin/sh
# basic test for hg debugrebuildstate
hg init repo
cd repo
touch foo bar
hg ci -Am 'add foo bar'
touch baz
hg add baz
hg rm bar
hg debugrebuildstate
echo '% state dump after'
hg debugstate --nodates | sort
echo '% status'
hg st -A