(jikstra, hpk) fix a logic bug introduced with the stock-string merge which set the better message only if it was empty

src/dc_mimeparser.rs

@@ -1212,11 +1212,8 @@ unsafe fn dc_mimeparser_add_single_part_if_known(
                                     info!(
                                         mimeparser.context,
                                         0,
-                                        "Simpliifed text: \n---\n{}\n--\n",
-                                        String::from_utf8_lossy(std::slice::from_raw_parts(
-                                            decoded_data as *const u8,
-                                            decoded_data_bytes as usize,
-                                        ))
+                                        "Simpliifed text: {}",
+                                        as_str(simplified_txt),
                                     );
 
                                     let mut part = dc_mimepart_new();