Don't check unibyte hostnames for pure-ASCII

* src/process.c (network_lookup_address_info_1): Only check multibyte
hostnames for pure-ASCII.

* test/src/process-tests.el (unibyte-domain-name): Test unibyte domain
names with network-lookup-address-info.

src/process.c

@@ -4537,7 +4537,7 @@ network_lookup_address_info_1 (Lisp_Object host, const char *service,
   Lisp_Object msg = Qt;
   int ret;
 
-  if (SBYTES (host) != SCHARS (host))
+  if (STRING_MULTIBYTE (host) && SBYTES (host) != SCHARS (host))
     error ("Non-ASCII hostname %s detected, please use puny-encode-domain",
            SSDATA (host));
   ret = getaddrinfo (SSDATA (host), service, hints, res);

test/src/process-tests.el

@@ -227,6 +227,10 @@
   (should-error (network-lookup-address-info "faß.de"))
   (should (length (network-lookup-address-info (puny-encode-domain "faß.de")))))
 
+(ert-deftest unibyte-domain-name ()
+  "Unibyte domain names should work"
+  (should (length (network-lookup-address-info (string-to-unibyte "google.com")))))
+
 (ert-deftest lookup-google ()
   "Check that we can look up google IP addresses"
   (let ((addresses-both (network-lookup-address-info "google.com"))