Uncomment most recent comment if commandline is empty when using toggle comment binding (#7137)

* functions/__fish_toggle_comment_commandline: Uncomment most recent comment if commandline is empty

* Refactor variable setting in functions/__fish_toggle_comment_commandline.fish

* Update changelog regarding toggle comment binding

CHANGELOG.rst

@@ -94,6 +94,8 @@ New or improved bindings
 -  ``__fish_prepend_sudo`` (Alt-S) now toggles a ``sudo`` prefix (#7012).
 -  ``__fish_prepend_sudo`` (Alt-S) now uses the previous commandline if the current one is empty,
    to simplify rerunning the previous command with ``sudo`` (#7079).
+- ``__fish_toggle_comment_commandline`` (Alt-#) now uncomments and presents the last comment
+  from history if the commandline is empty (#7137).
 
 Improved prompts
 ^^^^^^^^^^^^^^^^

share/functions/__fish_toggle_comment_commandline.fish

@@ -4,12 +4,13 @@
 # retrieving the command from the shell history and removing the comment chars.
 #
 # This deliberately does not execute the command when removing the comment characters to give you an
-# opportunity to modify the command.
+# opportunity to modify the command. Also if the commandline is empty, the most recently commented
+# out history item is uncommented and presented.
 
 function __fish_toggle_comment_commandline --description 'Comment/uncomment the current command'
     set -l cmdlines (commandline -b)
     if test "$cmdlines" = ""
-        return
+        history search -p "#" -z | read -z cmdlines
     end
     set -l cmdlines (printf '%s\n' '#'$cmdlines | string replace -r '^##' '')
     commandline -r $cmdlines