* Fetch logs by hash in blockchain database
* Fix tests
* Add unit test for branch block logs fetching
* Add docs that blocks must already be sorted
* Handle branch block cases properly
* typo: empty -> is_empty
* Remove return_empty_if_none by using a closure
* Use BTreeSet to avoid sorting again
* Move is_canon to BlockChain
* typo: pass value by reference
* Use loop and wrap inside blocks to simplify the code
Borrowed from https://github.com/paritytech/parity/pull/8463#discussion_r183453326
* typo: missed a comment
07aaca451c