fish: git_sw: Handle certain arguments to 'git switch'

Signed-off-by: Nathan Chancellor <[email protected]>

fish/functions/git_sw.fish

@@ -4,7 +4,18 @@
 
 function git_sw -d "git switch with fzf"
     if test (count $argv) -gt 0
-        set ref $argv
+        for arg in $argv
+            switch $arg
+                case -d --detach
+                    set -a git_switch_args $arg
+                case '*'
+                    set ref $arg
+            end
+        end
+        if not set -q ref
+            print_error "No ref supplied?"
+            return 1
+        end
     else
         set ref (git bf)
     end