fix lookup of potential comp unit candidates
fix lookup of potential comp unit candidates

In case we have already seen a basename of a candidate we dropped
additional candidates. Therefor we missed a precompiled cu when we
already had seen a source file. Since the content of a directory
is not ordered the result depended on the phase of the moon, mostly.

tony-o/deb-rakudodaily,cygx/rakudo,nbrown/rakudo,sergot/rakudo,tony-o/rakudo,cognominal/rakudo,cognominal/rakudo,paultcochrane/rakudo,raydiak/rakudo,zostay/rakudo,salortiz/rakudo,tbrowder/rakudo,paultcochrane/rakudo,niner/rakudo,sjn/rakudo,samcv/rakudo,teodozjan/rakudo,LLFourn/rakudo,cognominal/rakudo,ab5tract/rakudo,laben/rakudo,labster/rakudo,teodozjan/rakudo,zostay/rakudo,rakudo/rakudo,cygx/rakudo,labster/rakudo,skids/rakudo,retupmoca/rakudo,tony-o/deb-rakudodaily,usev6/rakudo,tbrowder/rakudo,lucasbuchala/rakudo,cygx/rakudo,labster/rakudo,azawawi/rakudo,usev6/rakudo,sergot/rakudo,paultcochrane/rakudo,ungrim97/rakudo,MasterDuke17/rakudo,ungrim97/rakudo,tony-o/rakudo,sjn/rakudo,labster/rakudo,nunorc/rakudo,ab5tract/rakudo,azawawi/rakudo,rakudo/rakudo,ungrim97/rakudo,raydiak/rakudo,MasterDuke17/rakudo,salortiz/rakudo,nunorc/rakudo,LLFourn/rakudo,sergot/rakudo,samcv/rakudo,Gnouc/rakudo,Leont/rakudo,usev6/rakudo,softmoth/rakudo,raydiak/rakudo,cognominal/rakudo,Leont/rakudo,cygx/rakudo,MasterDuke17/rakudo,tony-o/rakudo,salortiz/rakudo,teodozjan/rakudo,nbrown/rakudo,nbrown/rakudo,retupmoca/rakudo,samcv/rakudo,laben/rakudo,jonathanstowe/rakudo,lucasbuchala/rakudo,labster/rakudo,zhuomingliang/rakudo,awwaiid/rakudo,dankogai/rakudo,nbrown/rakudo,softmoth/rakudo,salortiz/rakudo,awwaiid/rakudo,sjn/rakudo,softmoth/rakudo,zhuomingliang/rakudo,awwaiid/rakudo,laben/rakudo,LLFourn/rakudo,awwaiid/rakudo,zhuomingliang/rakudo,LLFourn/rakudo,Gnouc/rakudo,skids/rakudo,nunorc/rakudo,Gnouc/rakudo,tony-o/rakudo,usev6/rakudo,jonathanstowe/rakudo,ab5tract/rakudo,tbrowder/rakudo,tbrowder/rakudo,MasterDuke17/rakudo,nunorc/rakudo,cognominal/rakudo,softmoth/rakudo,retupmoca/rakudo,tony-o/deb-rakudodaily,ungrim97/rakudo,dankogai/rakudo,ugexe/rakudo,jonathanstowe/rakudo,tony-o/deb-rakudodaily,b2gills/rakudo,tony-o/rakudo,jonathanstowe/rakudo,sjn/rakudo,salortiz/rakudo,rakudo/rakudo,ab5tract/rakudo,nbrown/rakudo,usev6/rakudo,Gnouc/rakudo,b2gills/rakudo,zostay/rakudo,awwaiid/rakudo,teodozjan/rakudo,Leont/rakudo,rakudo/rakudo,dankogai/rakudo,tony-o/rakudo,paultcochrane/rakudo,skids/rakudo,b2gills/rakudo,Leont/rakudo,dankogai/rakudo,labster/rakudo,dankogai/rakudo,nbrown/rakudo,MasterDuke17/rakudo,niner/rakudo,lucasbuchala/rakudo,zhuomingliang/rakudo,azawawi/rakudo,ugexe/rakudo,ugexe/rakudo,tony-o/deb-rakudodaily,ungrim97/rakudo,tbrowder/rakudo,laben/rakudo,samcv/rakudo,Gnouc/rakudo,skids/rakudo,paultcochrane/rakudo,sjn/rakudo,cygx/rakudo,LLFourn/rakudo,sergot/rakudo,samcv/rakudo,MasterDuke17/rakudo,ab5tract/rakudo,zostay/rakudo,Gnouc/rakudo,niner/rakudo,niner/rakudo,rakudo/rakudo,rakudo/rakudo,azawawi/rakudo,b2gills/rakudo,lucasbuchala/rakudo,skids/rakudo,tony-o/deb-rakudodaily,ugexe/rakudo,jonathanstowe/rakudo,ugexe/rakudo,lucasbuchala/rakudo,softmoth/rakudo,tony-o/deb-rakudodaily,salortiz/rakudo,tbrowder/rakudo,raydiak/rakudo,azawawi/rakudo,retupmoca/rakudo,b2gills/rakudo