topic: introduce a minimal extensions to enable topic on the server This small extensions simply expose topic in the branch. This should help getting minimal support for topic from various hosting solution (eg: bitbucket maybe ?) See extensions help for details.

branching: merge stable into default

pusoperation: wrap pushoperation __init__ directly This is how remote names does it. Using the same method should helps with compatibility when mixing the two extensions.

hgignore: fix .err matching patterns We don't want to ignore .err file outside of the 'tests/' directory.