Contributed by Steve Loughran.
* Fixes AbstractContractSeekTest test to use readFully
* Doesn't do this to AbstractContractUnbufferTest test as it changes the test too much.
Instead just notes in the error that this may be transient
The issue is that read(buffer) doesn't guarantee that the buffer is filled, only that it will
read up to a point, and that may be just be the amount of data left in the TCP packet.
readFully corrects for this, but using it in the unbuffer test runs the risk that what
is tested for in terms of unbuffering doesn't actually get validated.
2029556dbb