As of p.r. #5285 go-ipfs will be able to return a block regardless of it if is given in CidV0 or CidV1. Soon, we will switch the blockstore to work with multihashes instead of CIDs.

However, for a period of time there will still be nodes that work at the CID level instead of the multihash level. These older nodes are very likely to have most of there content is CidV0. This can create a small problem when we start switch to CIDv1 at the UX level. For example, if there is some content that was originally available at CidV0, but we display it to the user as a Base32 CidV1 and the user then copy and pastes the link and tries to retrieve it, they may not be able to retrieve the content if the only nodes that have it are the older nodes.

My question is, do we want to try to solve this at the bitswap level? What I am thinking is that bitswap firsts tries to get the content using the original CID version (in the above example CIDv1), then after a brief timeout (maybe 5 seconds) it also requests the CIDv0 version of the hash. Once it retrieves either version it cancels both requests (if that is possible).

@Stebalien @whyrusleeping thoughts? I don't know enough about bitswap yet to really give any meaningful solutions.