On upgrade to 0.7.4, multiwallet tokens don't work without iat

[TheTechmage]

For jwt tokens that have been created without the iat field, they will no longer be considered valid and the profile cannot be retrieved. The offending code is located here:
https://github.com/hyperledger/aries-cloudagent-python/blob/dbe0f09e2c89d2da2da744d1d751da0dd40498ad/aries_cloudagent/multitenant/base.py#L395-L411

This commit should resolve the issue, however. I believe that it goes against the spirit of the original code.

[swcurran]

Let's talk about this on the ACA-Pug call tomorrow. I'd like to understand the importance of this -- sounds bad...

[swcurran]

This was discussed at the ACA-Pug meeting, and it was pointed out that this was expected behaviour as part of this change -- PR #1725 comment.

Debatable whether this is a breaking change, but we've added a warning to the Changelog for 0.7.4.

The proposed change (above) would remove the impact of the #1725 change, which is not helpful.

Closing this issue.