Enumeration error when attempting to create/save an Allocation

[zebulasampedro]

Internal Server Error: /admin/projects/allocationrequest/60/
Traceback (most recent call last):
  File "/opt/rcamp/lib/python2.7/site-packages/django/core/handlers/base.py", line 132, in get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "/opt/rcamp/lib/python2.7/site-packages/django/contrib/admin/options.py", line 616, in wrapper
    return self.admin_site.admin_view(view)(*args, **kwargs)
  File "/opt/rcamp/lib/python2.7/site-packages/django/utils/decorators.py", line 110, in _wrapped_view
    response = view_func(request, *args, **kwargs)
  File "/opt/rcamp/lib/python2.7/site-packages/django/views/decorators/cache.py", line 57, in _wrapped_view_func
    response = view_func(request, *args, **kwargs)
  File "/opt/rcamp/lib/python2.7/site-packages/django/contrib/admin/sites.py", line 233, in inner
    return view(request, *args, **kwargs)
  File "/opt/rcamp/lib/python2.7/site-packages/django/contrib/admin/options.py", line 1519, in change_view
    return self.changeform_view(request, object_id, form_url, extra_context)
  File "/opt/rcamp/lib/python2.7/site-packages/django/utils/decorators.py", line 34, in _wrapper
    return bound_func(*args, **kwargs)
  File "/opt/rcamp/lib/python2.7/site-packages/django/utils/decorators.py", line 110, in _wrapped_view
    response = view_func(request, *args, **kwargs)
  File "/opt/rcamp/lib/python2.7/site-packages/django/utils/decorators.py", line 30, in bound_func
    return func.__get__(self, type(self))(*args2, **kwargs2)
  File "/opt/rcamp/lib/python2.7/site-packages/django/utils/decorators.py", line 145, in inner
    return func(*args, **kwargs)
  File "/opt/rcamp/lib/python2.7/site-packages/django/contrib/admin/options.py", line 1467, in changeform_view
    self.save_model(request, new_object, form, not add)
  File "/opt/rcamp/lib/python2.7/site-packages/django/contrib/admin/options.py", line 1078, in save_model
    obj.save()
  File "./projects/models.py", line 178, in save
    amount_awarded = self.amount_awarded
  File "./projects/models.py", line 91, in create_allocation_from_request
    alloc = self.create(**alloc_fields)
  File "/opt/rcamp/lib/python2.7/site-packages/django/db/models/manager.py", line 127, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "/opt/rcamp/lib/python2.7/site-packages/django/db/models/query.py", line 348, in create
    obj.save(force_insert=True, using=self.db)
  File "./projects/models.py", line 127, in save
    next_id = int(last_id) + 1
ValueError: invalid literal for int() with base 10: 'ucb69_summit1'