It took a couple of months, but FSF accepted the copyright assignment. 
And then I promptly forgot to follow up on this because I was in the 
middle of something else.  Sorry about that!

Supposedly I have not appeared in copyright.list for Automake yet.  (FSF 
signed on 2024-09-24, so I would expect to be in by now.)  Please let me 
know if I need to do anything, such as forward the mutually signed 
agreement PDF to someone.

Attached is v3 of the patch series.  Changes from v2:
   * Fixed a race condition
   * Fixed accidental discard of test script's final line if the output 
didn't end with a terminating newline
   * Moved the line prefixing logic to a separate function for 
readability and to make it easier to add comments for subtle points
   * The driver's own stderr is no longer mixed with the test script's 
stderr
   * Rewrote the new tests as *.tap
   * Docs now suggest `[stderr]' prefix instead of `<stderr>'
   * Minor improvements to Automake's own test infrastructure

Thanks,
Richard