size: Gracefully handle EPIPE.

* guix/scripts/size.scm (guix-size): Wrap body in 'leave-on-EPIPE'.

guix/scripts/size.scm

@@ -280,6 +280,7 @@ Report the size of PACKAGE and its dependencies.\n"))
         (()
          (leave (_ "missing store item argument\n")))
         ((file)
+         (leave-on-EPIPE
           (with-store store
             (run-with-store store
               (mlet* %store-monad ((item    (ensure-store-item file))
@@ -289,6 +290,6 @@ Report the size of PACKAGE and its dependencies.\n"))
                       (profile->page-map profile map-file)
                       (return #t))
                     (display-profile* profile)))
-             #:system system)))
+              #:system system))))
         ((files ...)
          (leave (_ "too many arguments\n")))))))