fix bug in constraint parsing
fix bug in constraint parsing

This fixes a bug in parsing invalid constraint values

Signed-off-by: Jordan Wilberding <220780119b0515e812290c52572d947e9668976c@gmail.com>

syl20bnr/relx,ethercrow/relx,Licenser/relx,erlware/relx,bitwalker/relx,priestjim/relx,lrascao/relx,zugolosian/relx,tsloughter/relx,umatomba/relx,timclassic/relx,bsmr-erlang/relx,RJ/relx,ingwinlu/relx