First: Best. Bug. Report. Ever.
Comments inline, though I don't know enough about the Windows side to
help much.
> Checking for contrib/isn with bigint-passing mismatch ok
> Creating catalog dump The
> process cannot access the file because it is being used by another
> process.
> *failure*
Your speculation that antivirus may be involved is worth trying out,
though the fact that a different upgrade worked does indeed suggest it's
probably not that.
When you shut down the 9.1.3 cluster did you make absolutely certain
there were no postgres.exe processes lurking around when you tested?
Given the incredible thouroughness of your report I imagine you did, but
it's worth checking, as a lingering `postgres.exe' could (I imagine)
cause such an issue. Not that it should ever happen.
Do you have the option of re-trying with your AV disabled or removed?
--
Craig Ringer