Actually the MIDI file contained a 0xC0 0x00 event, which is invalid but makes no difference to the rest.

Author: Jakob Dübel

test/serial-fuzzy-write.py

@@ -137,7 +137,7 @@
 # s.write(sysex_end)
 
 bootmsg = [ 0xf0, 0x7f, 0x7f, 0x4, 0x1, 0x7f, 0x7f, 0xf7, 0xb0, 0x0,
-            0x0, 0xb0, 0x20, 0x0, 0xc0, 0x00, 0x02, 0x0b0, 0x4d, 0x40,
+            0x0, 0xb0, 0x20, 0x0, 0xc0, 0x00, 0x0b0, 0x4d, 0x40,
             0xb0, 0x4c, 0x40, 0xb0, 0x46 , 0x40, 0xb0, 0xa, 0x40,
             0xb0, 0x49, 0x40, 0xb0, 0x4b, 0x40, 0xb0, 0x48 , 0x40,
             0xb0, 0x5b, 0xd, 0xb0, 0x5e, 0x0, 0xb0, 0x4a, 0x40, 0xb0,