Just a heads up that `prop_isomorphic_key_encode` is failing on master
(for me locally and at <https://github.com/datalad/datalad-extensions>):

```
$ git show --no-patch --format=reference
85e57d826 (Added a comment: streaming data and external backends, 2020-07-30)

$ stack exec -- git annex test -p prop_isomorphic_key_encode
Tests                     
  QuickCheck
    prop_isomorphic_key_encode: FAIL (0.03s)
      *** Failed! (after 601 tests):
      Exception:
        Data.ByteString.last: empty ByteString
        CallStack (from HasCallStack):
          error, called at libraries/bytestring/Data/ByteString.hs:1877:23 in bytestring-0.10.8.2:Data.ByteString
      Exception thrown while showing test case:
        Data.ByteString.last: empty ByteString
        CallStack (from HasCallStack):
          error, called at libraries/bytestring/Data/ByteString.hs:1877:23 in bytestring-0.10.8.2:Data.ByteString
      
      Use --quickcheck-replay=896100 to reproduce.

1 out of 1 tests failed (0.03s)
  (Failures above could be due to a bug in git-annex, or an incompatibility
   with utilities, such as git, installed on this system.)
```

I do not see this failure before f75be3216 (external backends wip,
2020-07-29).

Thanks in advance.

[[!meta author=kyle]]
[[!tag projects/datalad]]

> [[fixed|done]] and rest of test suite passing --[[Joey]]
