comint-accumulate-marker

[JD Smith]

`comint-accumulate-marker' should (I believe) be left at the process
mark when lines are accumulated.  To see this:

M-x shell
echo this is test 1 [RET]
echo this is test 2; [C-c SPC]
echo this is more test 2 [M-p]

The entire accumulated command should be replaced by the previous item
on the input history, but it is not, since the accumulate marker was
moved to the beginning of the 2nd line ("this is more test 2"), and use to
mark the beginning of the region which is replaced by the historical
command.

I noticed this while I was implementing a comint feature in my IDLWAVE
mode.  It occurs to me that this feature might be a useful option for
all comint modes, and might be better added there.  In a terminal
shell, using up arrow to recall history doesn't clobber the partially
complete command you are composin.  If you go back down, it is still
there (even if it's blank).  Not so in comint modes.  Going down with
M-p only wraps you around the input ring.  You can emulate the
terminal shell behavior by pretending there is another node on the
ring between index 0 and the last ring index, and save the partially
completed command when you stop "on" or "off" the ring.  I'd envision
this as a user option.

Do we have a 22.1 pre-release branch where only bug-fixes are being
applied, vs. HEAD where new features are being placed?