Just committed changes in bufmgr.c
Regress tests passed but need more specific tests,
as usually. Descr as in CVS:
> Check bufHdr->cntxDirty and call StartBufferIO in BufferSync()
> *before* acquiring shlock on buffer context. This way we should be
> protected against conflicts with FlushRelationBuffers.
> (Seems we never do excl lock and then StartBufferIO for the same
> buffer, so there should be no deadlock here, - but we'd better
> check this very soon).
Vadim
