Command line git is unable to clone with http from the userContent.git repository provided by the Jenkins git-usercontent-plugin if CSRF protection is enabled.

Steps to repeat the problem:

1. Download and unpack the JENKINS-48363.zip on a Linux computer
2. Change to the JENKINS-48363 directory and run bash ./README
3. Open a web browser to the Jenkins controller running on port 8080 and confirm that the Clone-userContent-with-git was successful
4. Stop the running bash ./README
5. Edit the README file to remove the DISABLE_CSRF setting from the java command line that starts Jenkins
6. Run bash ./README again
7. Open a web browser to the Jenkins controller running on port 8080 and confirm that the Clone-userContent-with-git fails

When the clone fails, it reports:

$ git clone http://localhost:8080/userContent.git
Cloning into 'userContent'...
error: RPC failed; HTTP 403 curl 22 The requested URL returned error: 403 No valid crumb was included in the request
fatal: The remote end hung up unexpectedly

The only workaround I've found is to disable CSRF protection.