The recent SHA1 collision got me thinking.. why do we always throw out the baby with the bathwater when moving to more modern hashing algorithms?
When GIT was written, they went with SHA1 hashes because MD5 was too old and had verified collisions. It is inevitable that given enough time and effort, any current and future algorithms will have problems and eventually demonstrable collisions.
So why not just choose to combine hashing algorithms, preferably the most modern, with the second most modern? Naturally, the hash length in bits would be longer, but seems to be a better way of future-proofing a system than just "use the best at the time of writing"
Is SHA1 hash concatenated with MD5 hash more or less likely to introduce a collision?