convert: allow the converter_source to say "skip this revision"
If getchanges returns a string, it's assumed to be the id of an
already converted revision. We map the current revision to the same
revision this converted revision was mapped to.
To allow skipping a root revision, getchanges can return the special
string 'hg-convert-skipped-revision' (a.k.a. common.SKIPREV), which
hopefully won't clash with any real id.
The converter_source is responsible for rewriting the parents of the
commit objects to make sure the revision graph makes sense.
#!/bin/sh
echo "[extensions]" >> $HGRCPATH
echo "convert=" >> $HGRCPATH
hg init a
cd a
echo a > a
hg ci -d'0 0' -Ama
hg cp a b
hg ci -d'1 0' -mb
hg rm a
hg ci -d'2 0' -mc
hg mv b a
hg ci -d'3 0' -md
echo a >> a
hg ci -d'4 0' -me
cd ..
hg convert a 2>&1 | grep -v 'subversion python bindings could not be loaded'
hg --cwd a-hg pull ../a