Invalid kernel is sometimes visible in CLI and GUI for installation, despite having failed build.

[rstrube]

Describe the bug
Pretty minor issue, but I thought I would report it as it might confuse new users.

Ubuntu mainline kernel 4.20.1 failed build for amd64 and is correctly marked as invalid. (see https://kernel.ubuntu.com/~kernel-ppa/mainline/v4.20.1/). However, there are times in both the CLI and GUI where the kernel does appear available for installation. If you attempt to install this kernel, only the header is installed.

To Reproduce
Completely remove /tmp/ukuu/* and ~/.cache/ukuu and restart the GUI or do ukuu --check. Intermittently the v4.20.1 kernel does appear as a new available point release in both the GUI and the CLI. Attempting to install this kernel will install the linux-header deb only.

Expected behavior
The v4.20.1 kernel should never appear as an available kernel (for amd64) in this situation. The linux-header deb should never be installed.

• Linux Distribution Name and Version: Ubuntu 18.10
• Desktop: Gnome
• Application Version: ukuu 18.5.1

[avsaponchik]

same stuff with 5.0-rc2.
once you see it with clean cache, then you install it, then it disappears.