F20: YUM - failure: repodata/repomd.xml from updates

[M. Fioretti]

Greetings,

I have, on a Fedora 20 x86_64 box, "yum update" failing with
lots of messages like the one in the subject, and others like:

ftp://ftp.ciril.fr/pub/linux/fedora/linux/updates/20/x86_64/repodata/repomd.xml: 
[Errno -1] repomd.xml does not match metalink for updates
Trying other mirror.

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This started happening to me yesterday, when I used bleachbit
(yes, even on the yum stuff in /var/) to make space on a
practically full root partition. However, I just discovered
somebody else reporting the SAME problem TODAY
(give or take a repo or two) here:

http://forums.fedoraforum.org/showthread.php?t=304378

but there is no mention of bleachbit there. "yum clean all" doesn't
change anything.

Earlier reports of similar problems turned out to be due to temporary 
problems
in the repos themselves:

http://forums.fedoraforum.org/showthread.php?t=291838

Is it the same today, or something else? What now?
TIA for any advice,

Marco