cloneContext

        pub fn cloneContext(self: Self, gpa: Allocator, ctx: Context) Oom!Self {
            var other: Self = .{};
            other.entries = try self.entries.clone(gpa);
            errdefer other.entries.deinit(gpa);

            if (self.index_header) |header| {
                // TODO: I'm pretty sure this could be memcpy'd instead of
                // doing all this work.
                const new_header = try IndexHeader.alloc(gpa, header.bit_index);
                other.insertAllEntriesIntoNewHeader(if (store_hash) {} else ctx, new_header);
                other.index_header = new_header;
            }
            return other;
        }