Fix entering insert mode after revision 78337a3816fd.

common/content/commandline.js

@@ -492,6 +492,7 @@ const CommandLine = Module("commandline", {
     },
 
     currentExtendedMode: Modes.boundProperty(),
+    _lastClearable: Modes.boundProperty(),
     _keepCommand: Modes.boundProperty(),
 
     multilineInputVisible: Modes.boundProperty({

common/content/modes.js

@@ -156,7 +156,7 @@ const Modes = Module("modes", {
     set: function (mainMode, extendedMode, params, stack) {
         params = params || {};
 
-        if (!stack && mainMode != null)
+        if (!stack && mainMode != null && this._modeStack.length > 1)
             this.reset();
 
         let push = mainMode != null && !(stack && stack.pop) &&