Revert "reader: Remove two more case-insensitive asserts"

See following commits.
This reverts commit 0778919e7f.

src/reader/reader.rs

@@ -1645,6 +1645,10 @@ fn combine_command_and_autosuggestion(
     if !string_prefixes_string(line, autosuggestion) && line.len() < autosuggestion.len() {
         // We have an autosuggestion which is not a prefix of the command line, i.e. a case
         // disagreement. Decide whose case we want to use.
+        assert!(string_prefixes_string_case_insensitive(
+            line,
+            autosuggestion
+        ));
         // Here we do something funny: if the last token of the command line contains any uppercase
         // characters, we use its case. Otherwise we use the case of the autosuggestion. This
         // is an idea from issue #335.
@@ -2003,6 +2007,11 @@ fn try_apply_edit_to_autosuggestion(&mut self, edit: &Edit) -> bool {
         // the autosuggestion.
         // This is also the main mechanism by which readline commands that don't change the command line
         // text avoid recomputing the autosuggestion.
+        assert!(string_prefixes_string_maybe_case_insensitive(
+            autosuggestion.icase,
+            &self.command_line.text()[autosuggestion.search_string_range.clone()],
+            &autosuggestion.text
+        ));
         let search_string_range = autosuggestion.search_string_range.clone();
 
         // This is a heuristic with false negatives but that seems fine.