Fix bootloaders not starting user application if the HWB is grounded during watchdog reset.

Bootloaders/MassStorage/BootloaderMassStorage.c

@@ -120,8 +120,19 @@ void Application_Jump_Check(void)
 			if (!(MCUSR & (1 << EXTRF)) || (MagicBootKey == MAGIC_BOOT_KEY))
 			  JumpToApplication = true;
 
+			/* Clear reset source */
 			MCUSR &= ~(1 << EXTRF);
 		}
+		else
+		{
+			/* If the reset source was the bootloader and the key is correct, clear it and jump to the application;
+			 * this can happen in the HWBE fuse is set, and the HBE pin is low during the watchdog reset */
+			if ((MCUSR & (1 << WDRF)) && (MagicBootKey == MAGIC_BOOT_KEY))
+				JumpToApplication = true;
+
+			/* Clear reset source */
+			MCUSR &= ~(1 << WDRF);
+		}
 	#endif
 
 	/* Don't run the user application if the reset vector is blank (no app loaded) */