comint-interrupt-subjob not quite working

[Rusi]

I have a comint-mode running gofer (tiny version of Haskell)

When the output is large I get
error in process filter: Invalid regexp: "Regular expression too big"
error in process filter: comint-output-filter: Invalid regexp: "Regular 
expression too big"

repeated 100s of times (in *Messages* )

C-c C-c (comint-interrupt-subjob) has no effect

Now if gofer is run outside emacs C-c works and interrupts it correctly
Likewise if run under emacs if there is nothing untoward happening emacs
passes on the interrupt correctly

However if there is this runaway behavior then emacs stops passing it to 
inferior
process

Killing gofer from outside gives back control to emacs