*shell* sometimes eats first char of command

[Dan Jacobson]

Sometimes in *shell*, apparently emacs loses track of where the prompt
ends and command begins.

t r u e <return> C-c C-p C-c C-c <return>

bash: rue: command not found

that was with PS1='$ '.  Here is some other scenes from real life. I
didn't keep track of my previous strokes though:
07:26 ~$ shar /tmp/f|mail -s bug bugs@gnus.org
07:29 1 ~$ bash: har: command not found
Null message body; hope that's ok

Yes, if I just typed the commands in without using any C-c stuff, it
probably wouldn't have occurred.