PostgreSQL version test is fragile

[Leo Soto M.]

On source:django/trunk/django/db/backends/postgresql/operations.py, _get_postgres_version does the following:

cursor.execute("SELECT version()")
self._postgres_version = [int(val) for val in cursor.fetchone()[0].split()[1].split('.')]

But that fails with some PostgreSQL installations on win32, where version() gives:

PostgreSQL 8.3.1, compiled by Visual C++ build 1400

So the last split() returns ['8', '3', '1,']. And int('1,') obviously fails.

This renders Django+PostgreSQL unusable on some installations (at least with Django 0.96)

[Russell Keith-Magee]

Essentially a dupe of #6433.