l2tp.sh from net in ubuntu_kernel_selftests failed with test not executable

It looks like it has the executable permission on the source tree:
phlin@tangerine:~/ubuntu-oem-5.6-focal/tools/testing/selftests/net$ ls -l l2tp.sh
-rwxrwxr-x 1 phlin phlin 9909 May 20 04:56 l2tp.sh

But somehow the source code from deb-src does not:
ubuntu@rizzo:~/autotest/client/tmp/ubuntu_kernel_selftests/src/linux$ head debian/changelog
linux-oem-5.6 (5.6.0-1011.11) focal; urgency=medium

  * focal/linux-oem-5.6: 5.6.0-1011.11 -proposed tracker (LP: #1880094)

  * Fix Pericom USB controller OHCI/EHCI PME# defect (LP: #1879321)
    - serial: 8250_pci: Move Pericom IDs to pci_ids.h
    - PCI: Avoid Pericom USB controller OHCI/EHCI PME# defect

  * Focal update: v5.6.14 upstream stable release (LP: #1879724)
    - KVM: nVMX: Consolidate nested MTF checks to helper function
ubuntu@rizzo:~/autotest/client/tmp/ubuntu_kernel_selftests/src/linux$ ls -l tools/testing/selftests/net/l2tp.sh
-rw-r--r-- 1 root root 9909 Mar 29 22:25 tools/testing/selftests/net/l2tp.sh

The deb-src package was downloaded with:
apt-get source --download-only linux-modules-5.6.0-1011-oem

With further investigation, this was disabled in the test case:
    #
    # this test breaks 5.0+ (and maybe earlier), disable it for now
    # 5/12/2019, LP#1854968
    #
    print("Disabling l2tp.sh")
    fn = 'linux/tools/testing/selftests/net/l2tp.sh'
    if os.path.exists(fn):
        cmd = 'chmod -x ' + fn
        utils.system(cmd)

With bug 1854968 fixed, we can see if this test can be added back.

https://kernel.ubuntu.com/git/ubuntu/autotest-client-tests.git/commit/?id=7dea7776ce431e5a1c550dc73b1d9ac0ba49698d