emacs: redirect undo to notmuch-tag-undo

The double remap is a bit ugly, but it seems better than adding
another layer of keymaps for those modes where notmuch-tag-undo makes
sense.

emacs/notmuch-hello.el

@@ -710,6 +710,9 @@ with `notmuch-hello-query-counts'."
   ;; that when we modify map it does not modify widget-keymap).
   (let ((map (make-composed-keymap (list (make-sparse-keymap) widget-keymap))))
     (set-keymap-parent map notmuch-common-keymap)
+    ;; Currently notmuch-hello-mode supports free text entry, but not
+    ;; tagging operations, so provide standard undo.
+    (define-key map [remap notmuch-tag-undo] #'undo)
     map)
   "Keymap for \"notmuch hello\" buffers.")
 

emacs/notmuch-lib.el

@@ -166,6 +166,7 @@ For example, if you wanted to remove an \"inbox\" tag and add an
     (define-key map (kbd "M-=") 'notmuch-refresh-all-buffers)
     (define-key map "G" 'notmuch-poll-and-refresh-this-buffer)
     (define-key map "j" 'notmuch-jump-search)
+    (define-key map [remap undo] 'notmuch-tag-undo)
     map)
   "Keymap shared by all notmuch modes.")
 

test/T315-emacs-tagging.sh

@@ -151,7 +151,16 @@ for mode in search show tree unthreaded; do
     output=$(notmuch search $os_x_darwin_thread | notmuch_search_sanitize)
     notmuch tag "-one-$mode" "-three-$mode" $os_x_darwin_thread
     test_expect_equal "$output" "thread:XXX   2009-11-18 [4/4] Jjgod Jiang, Alexander Botero-Lowry; [notmuch] Mac OS X/Darwin compatibility issues (inbox three-$mode unread)"
+
+    test_begin_subtest "undo tagging in $mode mode (via binding)"
+    test_emacs "(let ((notmuch-tag-history nil))
+      (notmuch-$mode \"$os_x_darwin_thread\")
+      (notmuch-test-wait)
+      (execute-kbd-macro \"+tag-to-be-undone-$mode\")
+      (execute-kbd-macro (kbd \"C-x u\"))
+      (notmuch-test-wait))"
+    count=$(notmuch count "tag:tag-to-be-undone-$mode")
+    test_expect_equal "$count" "0"
 done
 
-
 test_done