fix: ensure vendored grammar is in a clean state

Author: RoloEdits

helix-loader/src/grammar.rs

@@ -293,6 +293,8 @@ fn fetch_grammar(grammar: GrammarConfiguration) -> Result<FetchStatus> {
 
         // ensure the revision matches the configured revision
         if get_revision(&grammar_dir).as_ref() != Some(&revision) {
+            git(&grammar_dir, ["reset", "--hard"])?;
+            git(&grammar_dir, ["clean", "-fdx"])?;
             // Fetch the exact revision from the remote.
             // Supported by server-side git since v2.5.0 (July 2015),
             // enabled by default on major git hosts.