Fixed #10526 -- More fixes when specifying installed apps using "foo.*".

This adds a case that was missed in r9925: underscore handling.

Backport of r10078 from trunk.

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.0.X@10079 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/conf/__init__.py

@@ -7,6 +7,7 @@ a list of all possible variables.
 """
 
 import os
+import re
 import time     # Needed for Windows
 
 from django.conf import global_settings
@@ -91,8 +92,9 @@ class Settings(object):
                 appdir = os.path.dirname(__import__(app[:-2], {}, {}, ['']).__file__)
                 app_subdirs = os.listdir(appdir)
                 app_subdirs.sort()
+                name_pattern = re.compile(r'[a-zA-Z]\w*')
                 for d in app_subdirs:
-                    if d.isalnum() and d[0].isalpha() and os.path.isdir(os.path.join(appdir, d)):
+                    if name_pattern.match(d) and os.path.isdir(os.path.join(appdir, d)):
                         new_installed_apps.append('%s.%s' % (app[:-2], d))
             else:
                 new_installed_apps.append(app)

tests/regressiontests/app_loading/parent/__init__.py

@@ -1 +0,0 @@
-# not empty to make SVN happy

tests/regressiontests/app_loading/parent/app/__init__.py

@@ -1 +0,0 @@
-# not empty to make SVN happy

tests/regressiontests/app_loading/parent/app1/__init__.py

@@ -1 +0,0 @@
-# not empty to make SVN happy

tests/regressiontests/app_loading/tests.py

@@ -14,7 +14,7 @@ Test the globbing of INSTALLED_APPS.
 >>> settings = Settings('test_settings')
 
 >>> settings.INSTALLED_APPS
-['parent.app', 'parent.app1']
+['parent.app', 'parent.app1', 'parent.app_2']
 
 >>> sys.path = old_sys_path