Upgrade from postgresql-9.5alpha1 to postgresql-9.5alpha2 (Debian packages)

It looks like the catalog version has changed between 9.5alpha1 and
9.5alpha2:

FATAL: database files are incompatible with server
DETAIL: The database cluster was initialized with CATALOG_VERSION_NO 201506282,
but the server was compiled with CATALOG_VERSION_NO 201507281.
HINT: It looks like you need to initdb.

Normally, one would use pg_upgradecluster to do the upgrade, but
pg_upgradecluster assumes that the old and new version are installed in
parallel. Likewise, the low-level tool pg_upgrade needs the old bindir,
if I read the man-page correctly, and of course, apt-get upgrade
overwrites that, since it's just two versions of the same package
(unlike a major upgrade which is a new package).

So, what's the best way to do the upgrade?

* Copy the bindir before the upgrade (or restore from backup) to a safe
place and do pg_upgrade?
* Initdb a new cluster and restore yesterdays backup?
* Something else?

hp

--
_ | Peter J. Holzer | I want to forget all about both belts and
|_|_) | | suspenders; instead, I want to buy pants
| | | hjp(at)hjp(dot)at | that actually fit.
__/ | http://www.hjp.at/ | -- http://noncombatant.org/