test-convert-darcs: skip if we can't find the elementtree module
This patch is a bit dirty to avoid having to repeat the dance required
to import elementtree.
#!/bin/sh
hg init repo
cd repo
touch foo
hg ci -Am 'add foo'
hg up -C null
# this should be stored as a delta against rev 0
echo foo bar baz > foo
hg ci -Am 'add foo again'
hg debugindex .hg/store/data/foo.i