exec-env: set GOROOT and GOPATH unconditionally

Otherwise, existing values from the environment may continue to point to
a wrong version.

Refs asdf-community/asdf-direnv#149

Author: scop

bin/exec-env

@@ -3,11 +3,6 @@
 if [ "${ASDF_INSTALL_VERSION}" = 'system' ] ; then
 	unset -v GOROOT GOPATH
 else
-	if [[ "unset" == "${GOROOT:-unset}" ]] ; then
-	    export GOROOT=$ASDF_INSTALL_PATH/go
-	fi
-
-	if [[ "unset" == "${GOPATH:-unset}" ]] ; then
-	    export GOPATH=$ASDF_INSTALL_PATH/packages
-	fi
+	export GOROOT=$ASDF_INSTALL_PATH/go
+	export GOPATH=$ASDF_INSTALL_PATH/packages
 fi