gh-133740: Fix regression in locale.nl_langinfo(ALT_DIGITS) (GH-136237)

There is no need to temporary switch locale for items ALT_DIGITS and ERA
if the nl_langinfo() result is empty (most locales).

diff --git a/Modules/_localemodule.c b/Modules/_localemodule.c
index c1f56008b7c49e3c9680f51cc77835ed49fc527c..41e6d48b1dbd9bb96acced3f9cb19923c8be4c35 100644 (file)
--- a/Modules/_localemodule.c
+++ b/Modules/_localemodule.c
@@ -692,7 +692,7 @@ _locale_nl_langinfo_impl(PyObject *module, int item)
             result = result != NULL ? result : "";
             char *oldloc = NULL;
             if (langinfo_constants[i].category != LC_CTYPE
-                && (
+                && *result && (
 #ifdef __GLIBC__
                     // gh-133740: Always change the locale for ALT_DIGITS and ERA
 #  ifdef ALT_DIGITS