Comment 8 for bug 1775784

The issue tested by LTP testcase inotify08 has been fixed by commit:
   764baba80168 ("ovl: hash non-dir by lower inode for fsnotify")

>From this upstream commit:
"The issue dates back to initial version of overlayfs, but this
patch depends on ovl_inode code that was introduced in kernel v4.13."

Our Xenial 4.4 kernel doesn't have the ovl_inode code, so blacklist this
testcase for kernels older than 4.13.