What steps will reproduce the problem? 1. Open a read-only sketch (e.g. an example for a third-party library installed in SKETCHBOOK/libraries) that has .pde files. 2. Save the sketch, which will prompt you to pick a new location in which to save a copy (as the original is read only). Select one.

What is the expected output? What do you see instead? The files in the old sketch are renamed from .pde to .ino even though you saved a copy of the sketch. The old sketch should rename unchanged (i.e. maintain .pde extension); the newly saved copy should get .ino.

https://github.com/arduino/Arduino/commit/026794f1eb3f6df861158128334ca1fcbc6de82f