Use exec to run cwd target (#30)

multitool/private/cwd.template.sh

diff --git a/multitool/private/cwd.template.sh b/multitool/private/cwd.template.sh
index 2c42aa9..0f6270f 100644
--- a/multitool/private/cwd.template.sh
+++ b/multitool/private/cwd.template.sh
@@ -1,8 +1,4 @@
 #!/usr/bin/env bash
 
-tool="{{tool}}"
-execdir="$PWD"
-
-pushd "$BUILD_WORKING_DIRECTORY" > /dev/null
-"$execdir/$tool" "$@"
-popd > /dev/null
+tool="$PWD/{{tool}}"
+cd "$BUILD_WORKING_DIRECTORY" && exec "$tool" "$@"