Misleading error message from tlmgr

[Ralph Martin]

Dear Maintainers

While doing a tlmgr update today, my network connection dropped at some moment, and I got the following message:

tlmgr: main database at http://mirror.ox.ac.uk/sites/ctan.org/systems/texlive/tlnet is not signed: no access to cryptographic signature

Now, the (no access...) part of the message  is fine - but the (not signed...) part of the message  is not, and seems to be a faulty deduction arising from the lack of access. (When the network came back on, the tlmgr update went as expected). 

So, it might be appropriate to adjust this error message.

Otherwise, thanks for all your hard work.

Ralph Martin