fwupdmgr refresh fails due to invalid signature in 18.04

[hugh chao]

[Summary]
Due to the upstream bug[0], fwupd in 18.04 (1.2.14-0~18.04.2) is still suffering from the symptom.

And even Mario says so [1] "If you continue to encounter it on 1.3.x and earlier please try again in a few minutes.", but actually it's not "a few minutes thing", when this symptom happened, it might take days to recover.

So I am seeking the possibility to backport the patch [2] to bionic, since this will block ODM factory flow for days if they face this issue.

[Steps to reproduce]
1. Install stock ubuntu 18.04
2. Boot to desktop
3. run command "fwupdmgr refresh"

[Expected result]
`
Fetching metadata https://cdn.fwupd.org/downloads/firmware.xml.gz
Downloading… [***************************************] Less than one minute remaining…
Fetching signature https://cdn.fwupd.org/downloads/firmware.xml.gz.asc
`

[Actual result]

`
Fetching metadata https://cdn.fwupd.org/downloads/firmware.xml.gz
Downloading… [***************************************]
Fetching signature https://cdn.fwupd.org/downloads/firmware.xml.gz.asc

Failed to update metadata for lvfs: '48A6D80E4538BAC2' is not a valid signature
`

[0] https://github.com/fwupd/fwupd/issues/391
[1] https://github.com/fwupd/fwupd/issues/391#issuecomment-756941356
[2] https://github.com/fwupd/fwupd/commit/a1de20665a90decd6b3c5699016dbda42acd4746

[Atlas Yu (pseudoc)]

Sorry, I need to focus on some other urgent works, not assigning this to me any more.