[exim] Problems with ${if ..} conditions

Hello,

# ./exim -be '${if eq {a}{b} {true} {false}}'
Failed: missing } at end of "eq" condition
#

What's going on here? IMHO this condition is perfectly valid. I get the
same error no matter what condition I use. Writing the condition
directly inside an ACL doesn't change anythink as well.

# exim -bV
Exim version 4.50 #3 built 02-Mar-2005 22:36:48
Copyright (c) University of Cambridge 2004
Probably Berkeley DB version 1.8x (native mode)
Support for: OpenSSL Content_Scanning
Lookups: lsearch wildlsearch nwildlsearch iplsearch dbm dbmnz passwd
Authenticators: cyrus_sasl
Routers: accept dnslookup ipliteral manualroute queryprogram redirect
Transports: appendfile/maildir autoreply lmtp pipe smtp
Fixed never_users: 0
Configuration file is /usr/local/etc/exim/exim4.conf


Thanks in advance,

--Nikolaus, confused