bundlerepo: introduce method to find file starts and use it This moves us to the modern iter() technique instead of the `while True` pattern since it's easy. Factored out as a function because I'm about to need this in a second place.

bundlerevlog: use for loop over iterator instead of while True The iter() builtin has a neat pattern where you give it a callable of no arguments and a sentinel value, and you can then loop over the function calls like a normal iterator. This cleans up the code a little.

bundlerepo: use for loop over iterator instead of while True The iter() builtin has a neat pattern where you give it a callable of no arguments and a sentinel value, and you can then loop over the function calls like a normal iterator. This cleans up the code a little.

localrepo: jettison now-unused dirlog() method from localrepo

repair: build dirlogs using manifest, rather than repo shortcut method As before, this was rarely used, so let's get rid of the convenience method.

cmdutil: open dirlogs via manifest property, not via repo This was a convenience method that was rarely used, so let's get rid of it.

wirepeer: rename confusing `source` parameter It's named "url" everyplace else this method is defined, so let's be consistent.

develwarn: use the lock helper in local repo We have a helper function to know if a lock is taken. When checking lock usage we now use it instead of manually accessing the locks.