During testing, noted that ACCEPT 12345 would sometimes crop up as 02345 or 00345.  Have yet to
find out why.  I put in a 100-millisecond "pause" after sending the "12345", and after that
I never saw the truncated input again.  Very possibly this is pure coincidence, and this
problem will show up again.  If it does, I'll work on it further.

The ultimate solution is to figure out how to make the inferior accept and display data on a
different terminal instance than GDB does.  See the comment for f696b86f