rcutil: add a method to convert environment variables to config items...
rcutil: add a method to convert environment variables to config items
Handling config and environ priorities has been messy. Partially because we
don't have config layers - you either get all configs (sys + user), or none.
Ideally, environ like $EDITOR, $PAGER should be able to override the system
configs "ui.editor", "pager.pager". This patch provides the ability to
convert them into config items, so they can be inserted into the middle
config layer between system rc and user rc.
