How do I upgrade Postgres database in Cygwin?

How do I upgrade Postgres database in Cygwin?

I updated some Cygwin packages and now I can't start Postgres:
$ /usr/sbin/postmaster
FATAL: database files are incompatible with server
DETAIL: The data directory was initialized by PostgreSQL version 8.2,
which is not compatible with this version 9.2.4.
I tried pg_upgrade but you need to specify both the old and new binary.
Plus, pg_upgrade says it only works with 8.3.
I thought I could use setup-x86.exe to pick the previous version, which is
8.2.11-1, however when I install that, then I can't start Postgres:
$ /usr/sbin/postgres.exe
Bad system call (core dumped)