I was looking to study the history of Bitcoin forks including the 2013 incident that may or may not have been a Hard fork depending on your definition.
There is a paper that provides extensive detail on the history of all kind of forks on Bitocin, Ethereum and Ethereum Classic, you can read it here, Atomically Trading with Roger: Gambling on the success of a hardfork.
Here is the list of Forks so far,
The following content is sourced from the above paper,
So far, Bitcoin has implemented over six softforks. These softforks range from introducing rules to prevent miners creating coinbase transactions with duplicated identification hashes, requiring all ECDSA signatures to strictly enforce DER coding, and introducing both absolute and relative lock times for individual transaction outputs. In terms of implementation, this involves storing new information in the scriptsig of the coinbase transaction, constraining transaction validation rules or re-defining the use of special OP_NOP function. On the other hand, Bitcoin has experienced two accidental (and temporary) splits (i.e. Fork-1, Fork-2 emerged) that required miner intervention to remedy. The first split permitted a user to exploit an integer overflow bug and create 184 billion coins. This required miners to co-operatively extend a new blockchain without the coin creation transaction  and to enforce a soft-fork to prevent this exploit. The second split involved miners who upgraded to Bitcoin Core 0.8 accidentally creating blocks that were invalid for Bitcoin Core 0.7. Unfortunately, BerkeleyDB’s configuration in Bitcoin Core 0.7 was non-deterministic and as a result was not compatible with LevelDB’s configuration in Bitcoin Core 0.8. Resolving this fork required miners to immediately downgrade to Bitcoin Core 0.7 and abandon the forked blockchain. Next, the developers released Bitcoin Core 8.1 that enforced the activation of a hardfork12 after a two-month grace period for miners and users to upgrade
On their github:
Please reffer to githubs help page for searching issues.
This is just example of how you could use it in searching for "issue" from 2013-01-01 to 2013-12-31:
Full link for bitcoin's issues from that period core would be: https://github.com/bitcoin/bitcoin/search?utf8=%E2%9C%93&q=issue+created%3A%222013-01-01+..+2013-12-31%22&type=Issues
This would look for "bug" for the same periods:
I do not have enough reputation to post you more than 2 link:
You could apply the same on cards and projects