config: drop debug messages saying where config was read from `hg config --debug` includes lines like this: set config by: $EDITOR but also lines like this: $EDITOR: ui.editor=emacs -nw The `set config by` messages don't seem to provide much additional information over what we get from the `$EDITOR:`-type message. I could imagine wanting to see which values got overriden by a later entry, but that information is already not present. So let's just remove the first type of output. My next patch would otherwise amplify the redundant output (there would be one `set config by` for each line in `mergetools.rc`). Differential Revision: https://phab.mercurial-scm.org/D7627