current directory for multiple django instances on one Apache - django

Question

We are trying to run multiple django instances on the same Apache server. All sites share the same code (and settingsfile), but have a different working directory (with wsgi.py and a configfile with databaseparameters) and a different database. Version of Django is 1.6.2. The layout is as follows:
/bin/manage.py
/tttb/settings.py
/site1/wsgi.py
/config.txt
/site2/wsgi.py
/config.txt
Below is the current format of httpd.conf.
NameVirtualHost *:80
WSGIPythonPath "Z:/projects/bin/tttb"
# site1
# =======================================
<VirtualHost *:80>
ServerName site1
WSGIScriptAlias "/djangosite1" "Z:/projects/site1/wsgi.py"
<Directory "Z:/projects/site1">
Order allow,deny
Allow from all
AllowOverride None
Options None
Require all granted
</Directory>
</VirtualHost>
# site1
# =======================================
<VirtualHost *:80>
ServerName site2
WSGIScriptAlias "/djangosite2" "Z:/projects/site2/wsgi.py"
<Directory "Z:/projects/site2">
Order allow,deny
Allow from all
AllowOverride None
Options None
Require all granted
</Directory>
</VirtualHost>
Our wsgi.py files look like this:
import os,sys
bindir = os.path.join("Z:\\","projects","bin")
if bindir not in sys.path:
sys.path.append(bindir)
os.chdir(os.path.dirname(os.path.abspath(__file__)))
os.environ['DJANGO_SETTINGS_MODULE'] = 'tttb.settings'
from django.core.wsgi import get_wsgi_application
application = get_wsgi_application()
Contrary to similar questions on StackOverflow (see here or here) we are running on windows (XAMMP) so using WSGIApplicationGroup or WSGIProcessGroup is not possible. However, as first glance this setup works. We have even tested it both with and without virtualhosts. In both case it works OK.
Except for one detail: when we need to determine the current working directory ("."), the instances get mixed up. eg.
myfile = open(os.path.join(".","someresultfile.txt"),"r")
Initially, -immediately after restart of Apache-, the workdir is still determined correctly, but after having browsed to both sites once, the workingdirectory seems to get locked into one of both paths.
Probably there are other, similar leaks that we are not aware of, but this is the most obvious. We have also tried this without using virtualhosts, and it gives the same result.
Another weird behavior is that when using virtualhosts as above, the url http://www.domain.com/djangosite1 (on the general hostname) is still pointing to one of the djangosites. However, I would expect that it should should point to the subdirectory htdocs/djangosite1 (and fail, as this directory does not exist).
Any help on this one is appreciated.