logtoprocess: sends the canonical command name to the subprocess One of the use-case of logtoprocess is to monitor command duration. With the current code, we only get whatever command name the user typed (either abbreviated or aliased). This makes analytics on the collected data more difficult. Stores the canonical command name in the request object. Pass the stored canonical name in the `req.ui.log("commandfinish", ...)` call as keyword argument to not break potential string formatting. Pass the value as the environment variable named `LTP_COMMAND` to the called script. Differential Revision: https://phab.mercurial-scm.org/D4820