tests: fix a bug in sanitize_path_ that inhibited verbose output

* tests/test-lib.sh (sanitize_path_): Use "set -- ...", not "set - ...",
since the latter turns off the -x setting we rely on for VERBOSE=yes
output.

tests/test-lib.sh

@@ -30,7 +30,7 @@ sanitize_path_()
 {
   local saved_IFS=$IFS
     IFS=:
-    set - $PATH
+    set -- $PATH
   IFS=$saved_IFS
 
   local d d1