git: add clean-deleted-remotes command

scripts/default.nix

@@ -125,6 +125,12 @@
       zbar
       wl-clipboard
     ];
+    git_clean_remote_deleted = [
+      git
+      gnugrep
+      gawk
+      findutils
+    ];
     pint-fmt = [ ];
     powerplay-led-idle = [
       bash

scripts/git_clean_remote_deleted

@@ -0,0 +1,6 @@
+#!/bin/sh
+
+git branch -vv \
+| grep ': gone]' \
+| awk '{print $1}' \
+| xargs git branch -D