hostname: keep dots in hostname

src/hostname-setup.c

@@ -52,7 +52,8 @@ static char* strip_bad_chars(char *s) {
                     (*p >= 'A' && *p <= 'Z') ||
                     (*p >= '0' && *p <= '9') ||
                     *p == '-' ||
-                    *p == '_')
+                    *p == '_' ||
+                    *p == '.')
                         *(d++) = *p;
 
         *d = 0;