discovery: cleanup of variable names and comments

localrepo: give a sigh of relief when getting lock after waiting for it A message like this was sometimes shown when pushing: remote: waiting for lock on repository foo held by 'mercurial:20858' That could scare users, making them wonder whether the push actually succeeded. To mitigate that fear, issue an additional "warning" such as: got lock after 2 seconds The return value from lock.lock.lock() was unused - instead we return the delay. This also adds the first test coverage for waiting for locks.

convert: add tagmap option Tests have been updated.

convert: add tagmap logic Previously, there was no way to rewrite tags on the fly while converting. Now, we add similar logic to branchmap to provide a way to map old tags to new tags. Currently, this is not enabled since there is not yet a command-line option.

convert: avoid updating tags when there is nothing new Previously, when converting from a mercurial repo there would be an extraneous commit at the end of the convert process that would rewrite tags. Now, we check if there are any new tags before doing this rewriting.

convert: compare tags from all heads instead of just one Previously, the hg sink for puttags would just use one head for getting the old tags which would sometimes lead to tags disappearing. Now, we iterate over all heads and merge the results.