Finally found the root cause of the Android 4.3/4.4 trouble, and a fix is now in place!

As a bonus, it looks like I've fixed a problem accessing the environment on Android that had been worked around in an ugly way before.

Big thanks to my remote hands Michael Alan, Sören, and subito. All told they ran 19 separate tests to help me narrow down this tricky problem, often repeating long command lines on software keyboards.