gnu: guile-wisp: Simplify arguments and fix indentation.

* gnu/packages/guile.scm (guile-wisp)[arguments]: Slightly simplify and fix
indentation.

gnu/packages/guile.scm

@@ -1303,28 +1303,19 @@ key-value cache and store.")
                   (guix build utils)
                   (ice-9 rdelim)
                   (ice-9 popen))
-
        #:phases
        (modify-phases %standard-phases
-         (add-before 'configure 'substitute-before-config
-
-          (lambda* (#:key inputs #:allow-other-keys)
-            (let ((bash (assoc-ref inputs "bash")))
-              ;; Puts together some test files with /bin/bash hardcoded
+         (add-before 'configure 'patch-/usr/bin/env
+           (lambda _
              (substitute* "Makefile.in"
-                (("/usr/bin/env bash")
-                 (string-append bash "/bin/bash"))
+               (("/usr/bin/env bash") (which "bash"))
                (("\\$\\(GUILE_EFFECTIVE_VERSION\\)/site")
                 "site/$(GUILE_EFFECTIVE_VERSION)")) ;use the right order
-              #t)))
-
+             #t))
          ;; auto compilation breaks, but if we set HOME to /tmp,
          ;; that works ok
-         (add-before
-          'check 'auto-compile-hacky-workaround
-          (lambda _
-            (setenv "HOME" "/tmp")
-            #t))
+         (add-before 'check 'auto-compile-hacky-workaround
+           (lambda _ (setenv "HOME" "/tmp") #t))
          (add-after 'install 'install-go-files
            (lambda* (#:key outputs inputs #:allow-other-keys)
              (let* ((out (assoc-ref outputs "out"))