Error loading default app when using url_prefix

[DavidiBeMe]

Platform: Windows
py4web version: most recent from master

Issue:
When using the url_prefix=/testit, I see the following error for the default application:

Traceback (most recent call last):
File "c:\APPS\Anaconda3\workspace\py4web_src\py4web\core.py", line 1323, in import_app
module = importlib.machinery.SourceFileLoader(
File "", line 529, in _check_name_wrapper
File "", line 1029, in load_module
File "", line 854, in load_module
File "", line 274, in _load_module_shim
File "", line 711, in _load
File "", line 680, in _load_unlocked
File "", line 850, in exec_module
File "", line 228, in call_with_frames_removed
File "c:\APPS\Anaconda3\workspace\py4web_src\apps_default_init.py", line 6, in
def index():
File "c:\APPS\Anaconda3\workspace\py4web_src\py4web\core.py", line 972, in call
Reloader.register_route(app_name, short_path, self.kwargs, func)
File "c:\APPS\Anaconda3\workspace\py4web_src\py4web\core.py", line 1375, in register_route
bottle.route(rule, **kwargs)(dec_func)
File "C:\APPS\Anaconda3\envs\py4web_src\lib\site-packages\ombott\ombott.py", line 133, in decorator
self.add_route(rule, method, callback, name, overwrite=overwrite)
File "C:\APPS\Anaconda3\envs\py4web_src\lib\site-packages\ombott\ombott.py", line 125, in add_route
return self.router.add(rule, method, handler, name, overwrite=overwrite)
File "C:\APPS\Anaconda3\envs\py4web_src\lib\site-packages\ombott\router\radirouter.py", line 240, in add
return self._add(rule, methods, handler, name, meta=meta, overwrite=overwrite)
File "C:\APPS\Anaconda3\envs\py4web_src\lib\site-packages\ombott\router\radirouter.py", line 375, in _add
route = Route(rule)
File "C:\APPS\Anaconda3\envs\py4web_src\lib\site-packages\ombott\router\radirouter.py", line 55, in init
pattern, params, filters, pattern_out, filters_out = self.class.parse_rule(rule)
File "C:\APPS\Anaconda3\envs\py4web_src\lib\site-packages\ombott\router\radirouter.py", line 177, in parse_rule
assert rule[0] == '/'
IndexError: string index out of range