i believe this particular bustage is actually down to a broken url (http://www.multiprecision.org/downloads/mpc-0.8.2.tar.gz.asc) in that failure log.
Bug 1582726 Comment 15 Edit History
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i believe this particular bustage is actually down to a broken url (http://www.multiprecision.org/downloads/mpc-0.8.2.tar.gz.asc) in that failure log. see bug 1550816, comment 4.