tests(var_subst): ensure commands partially in variables work

test.sh

@@ -1166,4 +1166,16 @@ expecting <<EOF
 hello and goodbyehello$
 EOF
 
+when_run <<"EOF" "command partially in variable"
+touch file1 file2
+export CMD="s -a"
+l$CMD
+EOF
+expecting <<EOF
+.
+..
+file1
+file2
+EOF
+
 finalize