[SR-Users] Warning "constant value in if(...)"

Hi, I discovered that when kamailio (version 5.0.1) starts, if reports a waring on a 'if' command : May 11 11:26:20 vm-vse02-siprouter2 kamailio: WARNING: <core> [core/cfg.y:3378]: warn_at(): warning in config file //etc/kamailio/kamailio.cfg, line 978, column 6-13: constant value in if(...) The line 978 (in yellow) is part of the following routing below in my Kamailio.cfg : route[TO_MMM] { $var(mbxDN)=$null; # directory number containing mailbox number $var(uDigit)=$null; # application digits $var(i:NodePath)=$null; $var(TechNumber)=$null; $avp(nodeInx)=$null; # strip prefix from user in URI request user field $var(TechNumber) = $(rU{re.subst,/^(\+33|\+262|\+377|\+590|\+594|\+596|0)//}); # strip suffix from user in URI request user field - suffix headed by anything other than digit or '+' $var(TechNumber) = $(var(TechNumber){re.subst,/[^\+0-9].*//}); if (VM_TARGET_TECHNICAL_NUMBER!=$null) { $avp(vm_prefix) = VM_TARGET_TECHNICAL_NUMBER; } else { $avp(vm_prefix) = $(var(TechNumber){s.substr,0,5}); The same code with kamailio 3.3 doesn't report this warning. Also the same code exists in another part of the routine but don't report a warning. I have no idea of the impact of such warning. Also I'm looking for help to understand the problem. Thanks in advance for the answers. Cordialement Patrick GINHOUX