[Dovecot] Pigeonhole 0.3.4: Warning: sieve: encountered corrupt binary: re-compiling script

Hi all,

Upgraded to Dovecot 2.1.16 and Pigeonhole 0.3.4 yesterday. We use lmtp and sieve. I've now started to see in the logs the following entries:

Warning: Jz6kNv8AY1FdfQAAVMeomg: sieve: encountered corrupt binary: re-compiling script [script path]

The script then appears to run correctly and the message gets stored where ever it should be.

This only appears to be happening for a few users and although it happens on the majority of their messages it doesn't happen for every single one.

What's the best way to start debugging?

Thank, Dan