Took a look at your log file. Everything looks right except the last bit:
Removing temporary dir /var/projects/otm/otm_env/build...
No distributions matching the version for pytz (from django-celery==3.0.17->-r requirements.txt (line 11))
Exception information:
Traceback (most recent call last):
File "/var/projects/otm/otm_env/local/lib/python2.7/site-packages/pip/basecommand.py", line 134, in main
status = self.run(options, args)
File "/var/projects/otm/otm_env/local/lib/python2.7/site-packages/pip/commands/install.py", line 236, in run
requirement_set.prepare_files(finder, force_root_egg_info=self.bundle, bundle=self.bundle)
File "/var/projects/otm/otm_env/local/lib/python2.7/site-packages/pip/req.py", line 1085, in prepare_files
url = finder.find_requirement(req_to_install, upgrade=self.upgrade)
File "/var/projects/otm/otm_env/local/lib/python2.7/site-packages/pip/index.py", line 309, in find_requirement
raise DistributionNotFound('No distributions matching the version for %s' % req)
DistributionNotFound: No distributions matching the version for pytz (from django-celery==3.0.17->-r requirements.txt (line 11))
I can't tell if this means pip is floundering on pytz (a timezone library) or django-celery which might require pytz. I'd try removing either line that sounds like one of those from the OpenTreeMap requirements.txt file and seeing if pip installs everything correctly. If that works, we'll have isolated your problems to one of those two, and you might be able to try installing them manually.