with: use context manager for wlock in _writeactive

with: use context manager for wlock in _writerepo

sshpeer: make remotelock a context manager

lock: turn a lock into a Python context manager This lets us greatly simply acquire/release cycles. Code pattern before: try: lock = repo.lock() # zillions of lines of code finally: lock.release() And after: with repo.lock(): # ...

with: use context manager for I/O in changedfiles in patch

with: use context manager for file I/O in memusage