convert: handle past or foreign partial svn copies
Subversion allows revisions to be composed of subparts coming from revisions
before the parent or from other part of the repository. There is no simple
representation for these now, keep the changes but do not track their origins.
#!/bin/sh
hg init
echo % should fail
hg add .hg/00changelog.i
mkdir a
echo a > a/a
hg ci -Ama
ln -s a b
echo b > a/b
echo % should fail
hg add b/b
echo % should succeed
hg add b
echo % should still fail - maybe
hg add b/b
exit 0