setup/command-name: drop ".exe" in short form

pkgs/racket-pkgs/racket-doc/scribblings/raco/command.scrbl

@@ -83,7 +83,8 @@ Returns a string that identifies the current command. When
 short name of the @exec{raco} executable followed by a space and the
 command name. Otherwise, it is the short name of the current
 executable, as determined by stripping the path from the result of
-@racket[(find-system-path 'run-file)].
+@racket[(find-system-path 'run-file)]. In either case, on Windows, an
+@filepath{.exe} extension is removed from the executable name.
 
 The result of this function is suitable for use with
 @racket[command-line]. For example, the @exec{decompile} tool parses

racket/collects/raco/command-name.rkt

@@ -21,7 +21,13 @@
       (let-values ([(p) (find-system-path 'run-file)]
                    [(n) (current-command-name)])
         (let-values ([(base name dir?) (split-path p)])
-          (if n
-              (format "~a ~a" name n)
-              (path->string name)))))))
+          (let-values ([(name) (if (eq? (system-type) 'windows)
+                                   (string->path-element
+                                    (regexp-replace #rx"(?i:[.]exe)$"
+                                                    (path-element->string name)
+                                                    ""))
+                                   name)])
+            (if n
+                (format "~a ~a" name n)
+                (path->string name))))))))