obsolete: experimental flag to get debug about obsmarkers exchange The obsolescence markers exchange is still experimental. We (developer) need more information about what is going on. I'm adding an experimental flag to add display the amount of data exchanged during bundle2 exchanges.

bundle2: add an 'idx' argument to the 'getbundle2partsgenerator' This argument let extensions control in what order bundle2 part are generated server side during a pull. This is useful to ensure the transaction is in a proper state before some actions or hooks happens.

bundle2: add an 'idx' argument to the 'b2partsgenerator' This argument let extensions control in what order bundle2 part are generated client side during a push. This is useful to ensure the transaction is in a proper state before some actions or hooks happens.

rpms: create missing builds dir if it doesn't exist

rpms: for packages with their own python, put it in /opt/python-hg This is more compliant with the FHS and Fedora packaging guidelines.

branchcache: stay silent if failing to read cache files The warning has in some cases incorrectly attributed unrelated problems to rbc. Instead, just do like the branch head cache does and stay quiet when reading fails. The cache will be missing the first time a repo is used. It is a normal situation and there is no reason to make a note of that.

merge: better debug messages before/after invoking external merge tool

subrepo: use vfs.walk instead of os.walk "dirpath" in the tuple yielded by "vfs.walk()" is relative one from the root of specified vfs, and absolute path in the warning message is composed by "vfs.join()". On the other hand, target file "f" exists in "dirpath", and "reljoin()" is needed to unlink "f" by "vfs.unlink()".