Fix the version parsing to support Debian

[suhaibmujahid]

The bug already reported and the fix proposed by Marten KARL on Debian bug tracking system (https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=890646)

The fix aims to support the customized version string for some Debian postgresql packages. So, the version string 10.3 (Debian 10.3-1.pgdg90+1) will be split by the space to consider only the first part.

The following error raised when I used Debian's postgresql package. This because the customized version string in Debian makes the patch value having an invalid string rather than an integer.

  File "/lib/python3.6/site-packages/postgresql/driver/dbapi20.py", line 409, in connect
    return driver.connect(**params)
  File "/lib/python3.6/site-packages/postgresql/driver/pq3.py", line 3037, in connect
    c.connect()
  File "/lib/python3.6/site-packages/postgresql/driver/dbapi20.py", line 354, in connect
    super().connect(*args, **kw)
  File "/lib/python3.6/site-packages/postgresql/driver/pq3.py", line 2427, in connect
    self._establish()
  File "/lib/python3.6/site-packages/postgresql/driver/pq3.py", line 2559, in _establish
    self.version_info = pg_version.normalize(pg_version.split(sv))
  File "/lib/python3.6/site-packages/postgresql/versionstring.py", line 28, in split
    vlist = [int(x or '0') for x in v[:-1]]
  File "/lib/python3.6/site-packages/postgresql/versionstring.py", line 28, in <listcomp>
    vlist = [int(x or '0') for x in v[:-1]]
ValueError: invalid literal for int() with base 10: '3 (Debian 10'

By excluding the extra part form the version string, the package works fine.

[ThomasChr]

Note: This happens also on Ubuntu.

[jwp]

I'd recommend keeping this at the debian/ubuntu packaging level. The patch itself is a reasonable solution, but I'm disinclined to commit in fear of running into other packaging systems that wish to make the field inconsistent with what postgresql.org defines.

The versionstring module is unlikely to change unless postgresql.org changes their versioning strategy, so there should be little concern about having to update the patch in the future.

[greatvovan]

@jwp

The patch itself is a reasonable solution, but I'm disinclined to commit in fear of running into other packaging systems.

This is like waiting until the world adjusts for you rather than doing vice versa.

1. Any Postgres on Debian (and ancestors) now returns additional data in parenthesis.
2. Official Docker images of Postgres return additional data in parenthesis.

Your library basically cannot be used with recent versions of Postgres.

wish to make the field inconsistent with what postgresql.org defines.

Could you provide a link where the strict version format (as returned by pg_settings) is described?

[jwp]

Debian is not the world. This software is tested against releases made by postgresql.org.

[suhaibmujahid]

@jwp
I understand your point. I think it makes sense.

However, the patch will make the library compatible with packages that return additional data in parenthesis without breaking the backward compatibility with the packages that do not. So, it will stay consistent with what postgresql.org defines.

Merging the patch will save a lot of debugging time for many people.