discovery: properly exclude locally known but filtered heads The conditional was a bit too narrow and produced buggy result when a node was present in both common and heads (because it pleased the discovery) and it was locally known but filtered. This resulted in buggy getbundle request and server side crash.

test: make test-extdiff resilient to /usr/bin/echo My test machine has 'echo' in '/usb/bin/echo', #dontaskmewhy.

obsstore: make the invalid markers check wrap-able Some evolve user ignored the invalid markers for about two years and still have some of them in some repository. This lead to plain abort whenever mercurial try to open such repo. We need reinstall some way to clean this up in the evolve extension. For this purpose, we need the checker code wrap-able independently. This is scheduled for stable as this issue is blocking some evolve user.