Unable to use query starting with "-"

[RalfJung]

Calling rg -e -- (to search for all occurrences of "--") fails with

$ rg -e "--"
error: The argument '--regexp <pattern>...' requires a value but none was supplied

In contrast, the same pattern works for the usual GNU-style tools:

$  egrep -e "--" -R .
...

I am aware that I can work around this issue using e.g. [-]- as the pattern, but that should not be necessary.

[BurntSushi]

This might be a clap bug. Note that rg -e - works.

cc @kbknapp

[kbknapp]

It looks like it's due to the special casing of -- meaning "only free args follow" taking precedence over the -e allowing values to start with -. This should be a decently easy fix, I think I can knock it out later today if all goes well.

[BurntSushi]

@kbknapp If there were ever an example of a low priority bug, this would be it. :-) Thank you all the same though!