Renaming Organization Type to a name which already exists crashes with UniqueViolation error

[trendspotter]

Steps to reproduce (assumes default template with demo data):

1. Go to Organizations ->Organization types -> Create
2. Create a type filling in required name field as "NGO" (or any other existing value)
3. Click on Save and observe error

   Traceback (most recent call last):
   File "/srv/web2py/gluon/restricted.py", line 219, in restricted
   exec(ccode, environment)
   File "/srv/web2py/applications/eden/controllers/org.py", line 511, in <module>
   File "/srv/web2py/gluon/globals.py", line 429, in <lambda>
   self._caller = lambda f: f()
   File "/srv/web2py/applications/eden/controllers/org.py", line 181, in organisation_type
   return s3_rest_controller()
   File "/srv/web2py/applications/eden/models/00_utils.py", line 245, in s3_rest_controller
   output = r(**attr)
   File "/srv/web2py/applications/eden/modules/s3/s3rest.py", line 691, in __call__
   output = self.resource.crud(self, **attr)
   File "/srv/web2py/applications/eden/modules/s3/s3rest.py", line 1775, in __call__
   output = self.apply_method(r, **attr)
   File "/srv/web2py/applications/eden/modules/s3/s3crud.py", line 113, in apply_method
   output = self.select(r, **attr)
   File "/srv/web2py/applications/eden/modules/s3/s3crud.py", line 1280, in select
   form = self.create(r, **attr).get("form", None)
   File "/srv/web2py/applications/eden/modules/s3/s3crud.py", line 387, in create
   output["form"] = self.sqlform(request = request,
   File "/srv/web2py/applications/eden/modules/s3/s3forms.py", line 467, in __call__
   success, error = self.process(form,
   File "/srv/web2py/applications/eden/modules/s3/s3forms.py", line 668, in process
   if form.accepts(vars,
   File "/srv/web2py/gluon/sqlhtml.py", line 1989, in accepts
   self.vars.id = self.table.insert(**fields)
   File "/srv/web2py/gluon/packages/dal/pydal/objects.py", line 762, in insert
   ret = self._db._adapter.insert(self, row.op_values())
   File "/srv/web2py/gluon/packages/dal/pydal/adapters/base.py", line 487, in insert
   raise e
   File "/srv/web2py/gluon/packages/dal/pydal/adapters/base.py", line 482, in insert
   self.execute(query)
   File "/srv/web2py/gluon/packages/dal/pydal/adapters/__init__.py", line 67, in wrap
   return f(*args, **kwargs)
   File "/srv/web2py/gluon/packages/dal/pydal/adapters/base.py", line 413, in execute
   rv = self.cursor.execute(command, *args[1:], **kwargs)
   psycopg2.errors.UniqueViolation: duplicate key value violates unique constraint "org_organisation_type_name_key"
   DETAIL:  Key (name)=(NGO) already exists.