storkit: merge 437_bug_strip_prefix_ci_panics_on_multi_byte_utf_8_input

server/src/chat/transport/matrix/rmtree.rs

@@ -136,10 +136,8 @@ fn strip_mention<'a>(message: &'a str, bot_name: &str, bot_user_id: &str) -> &'a
 }
 
 fn strip_prefix_ci<'a>(text: &'a str, prefix: &str) -> Option<&'a str> {
-    if text.len() < prefix.len() {
-        return None;
-    }
-    if !text[..prefix.len()].eq_ignore_ascii_case(prefix) {
+    let candidate = text.get(..prefix.len())?;
+    if !candidate.eq_ignore_ascii_case(prefix) {
         return None;
     }
     let rest = &text[prefix.len()..];