logtoprocess: drop support for ui.log() call with invalid msg arguments (BC) Before, the logtoprocess extension put a formatted message into $MSG1, and its arguments to $MSG2... If the specified arguments couldn't be formatted because of a caller bug, an unformatted message was passed in to $MSG1 instead of exploding. This behavior doesn't make sense. Since I'm planning to formalize the ui.log() interface such that we'll no longer have to extend the ui class, I want to remove any features not conforming to the ui.log() API. So this patch removes the support for ill-formed arguments, and $MSG{n} (where n > 1) parameters which seems useless as long as the message can be formatted. The $MSG1 variable isn't renamed for the maximum compatibility. In future patches, a formatted msg will be passed to a processlogger object, instead of overriding the ui.log() function. .. bc:: The logtoprocess extension no longer supports invalid ``ui.log()`` arguments. A log message is always formatted and passed in to the ``$MSG1`` environment variable.