Fixed saving a map as a scenario not enabling scenario editor tools

(cherry-picked from commit 4bda3e7311)

changelog.md

@@ -55,6 +55,8 @@
      * S11: added custom graphics for the citadel.
      * S12: clarified the alien bodies' weaknesses.
      * Various visual improvements.
+ ### Editor
+   * Fixed saving a map as a scenario not enabling scenario editor tools.
  ### Graphics
    * Tweaked the Ruffian's attack animation timing.
    * New attack animation for the Peasant.

src/editor/map/map_context.cpp

@@ -606,6 +606,9 @@ bool map_context::save_scenario()
 		throw editor_map_save_exception(msg);
 	}
 
+	// After saving the map as a scenario, it's no longer a pure map.
+	pure_map_ = false;
+
 	// TODO the return value of this method does not need to be boolean.
 	// We either return true or there is an exception thrown.
 	return true;