If TZ environment variable is changed call tzset().

# Although man page for tzset() says it should be called automaticly
# by some of the time related functions, IRL this doesn't happen.
# PR: 3977, 4732, 5510, 6972, 7203, 8502, 8609

ext/standard/basic_functions.c

@@ -1059,6 +1059,9 @@ PHP_FUNCTION(putenv)
 
 		if ((ret=putenv(pe.putenv_string))==0) { /* success */
 			zend_hash_add(&BG(putenv_ht),pe.key,pe.key_len+1,(void **) &pe,sizeof(putenv_entry),NULL);
+#ifdef HAVE_TZSET
+			if(!strncmp(pe.key,"TZ",2)) tzset();
+#endif
 			RETURN_TRUE;
 		} else {
 			efree(pe.putenv_string);