There's some who reported the issue was because of plgSystemKoowa in the PBF chat today. The component isn't structured like a normal Joomla component anymore, so anything expecting that will cause issues. Otherwise I've had the extension installed on the current CMS git head all day and had no issues other than my own missed cleanups from refactoring.

I installed it under a fresh J3.3.7-dev installation, no other components installed. For building the package I use the build.sh script.
When I looked up the paths variable in the display controler I saw this directory /administrator/templates/isis/html/com_patchtester/pulls. But after installation I do not have this directory. So I copyed the files manually there and then the error disappears.
Do you use the build script?

$paths should contain two paths, one for the template override and one in the component's folder. So you should have /administrator/templates/isis/html/com_patchtester/pulls then /administrator/components/com_patchtester/PatchTester/View/pulls/tmpl in the queue. Can you verify that and that you have the files in the right place?

The /administrator/templates/isis/html/com_patchtester/pulls directory doesn´t exist when I install a package build with the script. When I manually copy the files there, the patchtester is operating.
In /administrator/components/com_patchtester/PatchTester/View/pulls/tmpl I have three files (default.php default_errors.php default_items.php).

The directory shouldn't exist, the code's there for template override support (there are Hathor overrides in the repo). Weird how that isn't working for you but works OK for me on my local environment and my own site.

Do you have a build version so I can compare it with "my" build?

Any way you can test this with the new package?

Works for me now. Thanks!