[Edgy] python-distutils class assumes pycentral if DEB_PYTHON_SYSTEM not defined

Adding a patch to wrap 2 cases of incomplete tests inside ifdef DEB_PYTHON_SYSTEM clauses.

Thanks for your bug report. Please take a closer look at python-distutils.mk.in and especially at the beginning of the file (starting from line 51):

--- 8< ---
ifeq (pysupport, $(DEB_PYTHON_SYSTEM))
(...)
else
  ifeq (pycentral, $(DEB_PYTHON_SYSTEM))
(...)
  else
    ifneq (, $(DEB_PYTHON_SYSTEM))
      $(error unsupported Python system: $(DEB_PYTHON_SYSTEM) (select either pysupport or pycentral))
    else
(...)
      ifneq (, $(cdbs_use_xs_field))
        $(error Your package uses the new Python policy; you must set DEB_PYTHON_SYSTEM to "pysupport" or "pycentral".)
      endif
(...)
    endif # unknown method
  endif # pycentral
endif # pysupport
--- 8< ---

Therefore if you try to build a package following the new python policy (e.g. if there's a debian/pycompat file) and without defining DEB_PYTHON_SYSTEM the build will fail. If cdbs can't find a clue about whether the package follows the new or the old policy and if DEB_PYTHON_SYSTEM is not defined then the package will be built following the old policy (and it will display a big fat warning ;))

Jérémie Corbier wrote:
> Therefore if you try to build a package following the new python policy
> (e.g. if there's a debian/pycompat file) and without defining
> DEB_PYTHON_SYSTEM the build will fail. If cdbs can't find a clue about
> whether the package follows the new or the old policy and if
> DEB_PYTHON_SYSTEM is not defined then the package will be built
> following the old policy (and it will display a big fat warning ;))

Actually, this is wrong.

It will display a big fat warning (as it should) and it attempts to
build without the new system, but even still it will call dh_pycentral.
if you take a look at the patch, it will become quite obvious why this
happens. The cdbs makefile only tests if DEB_PYTHON_SYSTEM matches
pysupport and assumes that pycentral is the only other logical choice
without taking in to account that there might be cases where this if
clauses are hit without DEB_PYTHON_SYSTEM being defined.

So, even if cdbs is supposed to fall back to building with the old
system, it will build with an uninitialized pycentral support instead.

- s

Nope. It doesn't work like that. Your patch modifies the new policy part of python-distutils.mk:

--- 8< ---
ifndef DEB_PYTHON_SYSTEM
#### old policy method ####
(...)
else
#### new policy methods ####
(... patch applies here ...)
endif
--- 8< ---

And this part can only be reached if either pysupport or pycentral is used.

Jérémie Corbier wrote:
> And this part can only be reached if either pysupport or pycentral is
> used.

Hmm..

I must be loosing it here. For some reason i can't reproduce this
anymore either. Or it might be that it was a bug in my packaging that i
hit without realizing it. Oh well.

Sorry for bugging you (pun intended ;)

- S