[Python-apps-team] Bug#920977: Breaks loading of db backends in Trac

[Julien Cristau]

Control: severity -1 important

On 2/2/19 11:00 AM, Julien Cristau wrote:
> On 1/31/19 9:11 AM, Andras Korn wrote:
>> Package: mercurial-common
>> Version: 4.8.2-1
>> Severity: important
>>
>> Hi,
>>
>> as long as mercurial-common is installed, the postgres and sqlite db backend driver of Trac won't load:
>>
>> 2019-01-31 08:58:49,372 Trac[loader] ERROR: Skipping "trac.db.postgres = trac.db.postgres_backend": 
>> Traceback (most recent call last):
>>   File "/usr/lib/python2.7/dist-packages/trac/loader.py", line 77, in _load_eggs
>>     entry.load(require=True)
>>   File "/usr/lib/python2.7/dist-packages/pkg_resources/__init__.py", line 2346, in load
>>     return self.resolve()
>>   File "/usr/lib/python2.7/dist-packages/pkg_resources/__init__.py", line 2352, in resolve
>>     module = __import__(self.module_name, fromlist=['__name__'], level=0)
>>   File "/usr/lib/python2.7/dist-packages/hgdemandimport/demandimportpy2.py", line 172, in _demandimport
>>     return _hgextimport(_origimport, name, globals, locals, fromlist, level)
>>   File "/usr/lib/python2.7/dist-packages/hgdemandimport/demandimportpy2.py", line 43, in _hgextimport
>>     return importfunc(name, globals, *args, **kwargs)
>>   File "/usr/lib/python2.7/dist-packages/trac/db/postgres_backend.py", line 46, in <module>
>>     psycopg2_version = get_pkginfo(psycopg).get('version',
>>   File "/usr/lib/python2.7/dist-packages/trac/util/__init__.py", line 806, in get_pkginfo
>>     metadata = 'METADATA' if dist.has_metadata('METADATA') else 'PKG-INFO'
>>   File "/usr/lib/python2.7/dist-packages/hgdemandimport/demandimportpy2.py", line 151, in __getattr__
>>     return getattr(self._module, attr)
>> AttributeError: 'module' object has no attribute 'has_metadata'
>> 2019-01-31 08:58:49,372 Trac[loader] DEBUG: Loading plugin "trac.db.sqlite" from "/usr/lib/python2.7/dist-packages"
>> 2019-01-31 08:58:49,374 Trac[loader] ERROR: Skipping "trac.db.sqlite = trac.db.sqlite_backend": 
>> Traceback (most recent call last):
>>   File "/usr/lib/python2.7/dist-packages/trac/loader.py", line 77, in _load_eggs
>>     entry.load(require=True)
>>   File "/usr/lib/python2.7/dist-packages/pkg_resources/__init__.py", line 2346, in load
>>     return self.resolve()
>>   File "/usr/lib/python2.7/dist-packages/pkg_resources/__init__.py", line 2352, in resolve
>>     module = __import__(self.module_name, fromlist=['__name__'], level=0)
>>   File "/usr/lib/python2.7/dist-packages/hgdemandimport/demandimportpy2.py", line 172, in _demandimport
>>     return _hgextimport(_origimport, name, globals, locals, fromlist, level)
>>   File "/usr/lib/python2.7/dist-packages/hgdemandimport/demandimportpy2.py", line 43, in _hgextimport
>>     return importfunc(name, globals, *args, **kwargs)
>>   File "/usr/lib/python2.7/dist-packages/trac/db/sqlite_backend.py", line 45, in <module>
>>     pysqlite_version_string = get_pkginfo(sqlite).get('version',
>>   File "/usr/lib/python2.7/dist-packages/trac/util/__init__.py", line 806, in get_pkginfo
>>     metadata = 'METADATA' if dist.has_metadata('METADATA') else 'PKG-INFO'
>>   File "/usr/lib/python2.7/dist-packages/hgdemandimport/demandimportpy2.py", line 151, in __getattr__
>>     return getattr(self._module, attr)
>> AttributeError: 'module' object has no attribute 'has_metadata'
>>
>> I don't understand what the connection is, but removing mercurial-common
>> (which ships
>> /usr/lib/python2.7/dist-packages/hgdemandimport/demandimportpy2.py) helps.
>>
> As far as I can tell for this to happen something must have called
> hgdemandimport.enable().  Can you track down what that is?
> 
Looks like this might be it:

https://trac.edgewall.org/browser/mercurial-plugin/tracext/hg/backend.py#L70

Trac maintainers, is there any chance trac could stop doing this?  Using
demandimport in such an application seems like a recipe for trouble.

Cheers,
Julien