[Exim] Problematic default filename generation in exim4

Hi All,

I have a transport in exim4 that delivers to a maildir, everything is fine
except that the following error occurs when a delivery is attempted:

2003-06-11 13:53:36 19Q56b-0004yl-D1 == test@??? R=virt_user
T=virt_delivery defer (0): Expansion of "q${base62:$tod_epoch}-$inode"
(directory_file for virt_delivery transport) failed: argument for base62
operator is "2003-06-11", which is not a decimal number

If I manually set directory_file and replace $tod_epoch with ${tod_epoch}, it
works. Obviously I can live with this, but it'd be nice to find out just why
the epoch value is being converted to 2003-06-11 (I imagine the remainder of the
time is being cut off due to there being a space after 11). Does anyone have any
ideas?

The system is running RedHat 7.3 with exim 4.20.

Cheers,

Mike