Fix $*EXECUTABLE path construction after a chdir
Fix $*EXECUTABLE path construction after a chdir

Sets the CWD of the $*EXECUTABLE path before it can be changed.

Fixes:
$ install/bin/perl6 -e 'chdir "install"; say $*EXECUTABLE.absolute.perl;'
"/Users/ugexe/.rakudobrew/moar-blead-master/install/install/bin/perl6"
Gnouc/rakudo,salortiz/rakudo,rakudo/rakudo,salortiz/rakudo,salortiz/rakudo,labster/rakudo,nbrown/rakudo,labster/rakudo,salortiz/rakudo,nbrown/rakudo,nbrown/rakudo,tbrowder/rakudo,tbrowder/rakudo,labster/rakudo,labster/rakudo,rakudo/rakudo,tony-o/rakudo,salortiz/rakudo,softmoth/rakudo,Gnouc/rakudo,tony-o/rakudo,Gnouc/rakudo,Gnouc/rakudo,Gnouc/rakudo,softmoth/rakudo,MasterDuke17/rakudo,MasterDuke17/rakudo,tbrowder/rakudo,tony-o/rakudo,MasterDuke17/rakudo,salortiz/rakudo,rakudo/rakudo,nbrown/rakudo,tbrowder/rakudo,softmoth/rakudo,tony-o/rakudo,tony-o/rakudo,nbrown/rakudo,rakudo/rakudo,labster/rakudo,nbrown/rakudo,softmoth/rakudo,rakudo/rakudo,softmoth/rakudo,labster/rakudo,MasterDuke17/rakudo,tony-o/rakudo,MasterDuke17/rakudo,Gnouc/rakudo,tbrowder/rakudo,rakudo/rakudo,MasterDuke17/rakudo,tbrowder/rakudo