config: don't set source when no source is specified - don't overwrite with '' This prevents ui.fixconfig from overwriting the source of paths and it will thus show up in showconfig --debug.

config: give a useful hint of source for the most common command line settings 'hg showconfig --debug' will instead of: none: ui.verbose=False give the better hint: --verbose: ui.verbose=False

config: backout 77f1f206e135 - 743daa601445 removed the only use of overlay