correct typo in runtime paths

tests/test-langs.rkt

@@ -32,15 +32,16 @@
 (check-equal? ptree:doc '(pagetree-root (index (brother sister))))
 
 (define (run path)
-  (with-output-to-string (λ() (system (format "racket ~a" path)))))
+  (define cmd-string (format "racket ~a" path))
+  (with-output-to-string (λ() (system cmd-string))))
 
 (define-runtime-path test.ptree "test.ptree")
 (check-equal? (run test.ptree) "'(pagetree-root test ====)")
 (define-runtime-path test.html.pm "test.html.pm")
-(check-equal? (run "test.html.pm") "'(root \"test\" \"\\n\" \"====\")")
+(check-equal? (run test.html.pm) "'(root \"test\" \"\\n\" \"====\")")
 (define-runtime-path test.html.pmd "test.html.pmd")
-(check-equal? (run "test.html.pmd") "'(root (h1 ((id \"test\")) \"test\"))")
+(check-equal? (run test.html.pmd) "'(root (h1 ((id \"test\")) \"test\"))")
 (define-runtime-path test.html.pp "test.html.pp")
-(check-equal? (run "test.html.pp") "test\n====")
+(check-equal? (run test.html.pp) "test\n====")
 (define-runtime-path test.no-ext "test.no-ext")
-(check-equal? (run "test.no-ext") "test\n====")
+(check-equal? (run test.no-ext) "test\n====")