decide to not implement regex support (yet) (#427)

This is something for git-repository anyway, but it seems like
a lot of work for a rarely used feature and a big dependency which
might not ever be faithfully implemented as the regex engines will
probably differ.

crate-status.md

@@ -416,6 +416,8 @@ See its [README.md](https://github.com/Byron/gitoxide/blob/main/git-lock/README.
         * [ ] support for `GIT_CEILING_DIRECTORIES` environment variable
         * [ ] handle other non-discovery modes and provide control over environment variable usage required in applications
     * [ ] rev-parse
+        - **unsupported**
+            * regex 
     * [x] instantiation
     * [x] access to refs and objects
     * **traverse** 

git-revision/tests/spec/parse.rs

@@ -105,6 +105,14 @@ mod revision {
         assert!(rec.kind.is_none());
         assert_eq!(rec.resolve_ref_input.unwrap(), "HEAD");
     }
+
+    #[test]
+    #[ignore]
+    fn refname_with_head_prefix() {
+        let rec = parse("HEADfake");
+        assert!(rec.kind.is_none());
+        assert_eq!(rec.resolve_ref_input.unwrap(), "HEADfake");
+    }
 }
 
 mod range {