msg

src/locales/en.json

@@ -154,7 +154,7 @@
   "pad.userlist.guest": "Guest",
   "pad.userlist.deny": "Deny",
   "pad.userlist.approve": "Approve",
-  "pad.editbar.clearcolors": "Clear authorship colors on entire document?",
+  "pad.editbar.clearcolors": "Clear authorship colors on entire document? This cannot be undone",
 
   "pad.impexp.importbutton": "Import Now",
   "pad.impexp.importing": "Importing...",

src/locales/qqq.json

@@ -113,7 +113,7 @@
 	"pad.userlist.guest": "Preceded by the link text which is labeled {{msg-etherpadlite|Pad.userlist.approve}}.\n{{Identical|Guest}}",
 	"pad.userlist.deny": "Used as link text.\n\nFollowed by the link which is labeled {{msg-etherpadlite|Pad.userlist.approve}}.",
 	"pad.userlist.approve": "Used as link text.\n\nPreceded by the link which is labeled {{msg-etherpadlite|Pad.userlist.deny}}.\n\nFollowed by the message {{msg-etherpadlite|Pad.userlist.guest}}.\n{{Identical|Approve}}",
-	"pad.editbar.clearcolors": "Used as confirmation message (JavaScript <code>confirm()</code> function).\n\nThis message means \"Are you sure you want to clear authorship colors on entire document?\".",
+	"pad.editbar.clearcolors": "Used as confirmation message (JavaScript <code>confirm()</code> function).\n\nThis message means \"Are you sure you want to clear authorship colors on entire document? This cannot be undone\".",
 	"pad.impexp.importbutton": "Used as label for the Submit button.",
 	"pad.impexp.importing": "Used to indicate that the file is being imported.\n{{Identical|Importing}}",
 	"pad.impexp.confirmimport": "Used as confirmation message (JavaScript <code>confirm()</code> function).",

src/static/js/undomodule.js

@@ -253,7 +253,15 @@ var undoModule = (function()
       }
       if (!merged)
       {
-        stack.pushEvent(event);
+        /*
+         * Push the event on the undo stack only if it exists, and if it's
+         * not a "clearauthorship". This disallows undoing the removal of the
+         * authorship colors, but is a necessary stopgap measure against
+         * https://github.com/ether/etherpad-lite/issues/2802
+         */
+        if (event && (event.eventType !== "clearauthorship")) {
+          stack.pushEvent(event);
+        }
       }
       undoPtr = 0;
     }