evolve: use more specific key name to store in evolvestate
Now, as we also relocate divergent cset if required, so let's use
more specific key to track the relocation of "divergent" and "other".
Test that share-clones use the cache in the original repository.
$ . $TESTDIR/testlib/common.sh
$ hg init share-base
$ cd share-base/
$ cat >> .hg/hgrc <<EOF
> [extensions]
> evolve=
> share=
> EOF
$ hg debugbuilddag .+3:branchpoint+4*branchpoint+2
$ cd ..
$ hg --config extensions.share= share -U share-base share-client
$ cd share-client
$ hg debugupdatecache
$ test -d .hg/cache
[1]
$ test -d ../share-base/.hg/cache