I wanted to follow up real quick, in case someone else finds this thread upon running into the same problem (as I did).
After changing the file /usr/share/xbps.d/00-repository-main.conf back to its original format of containing just
and a new line, I was getting mtime mismatches (instead of hash mismatches). I forget the precise phrasing, but something to the effect that the registered mtime was say 1492072521 vs the current mtime reading of 1514643346.
Those are apparently second counts from the beginning of the Unix epoch, and to extract the date for feeding into ‘touch’ I used
date -d “@1492072521”
This must be obvious to mostly everyone around here, but it wasn’t to me… Anyway, no more errors afterwards.