This also bumps the stable nixpkgs to 20.09 as of 2020-11-21, because
there is some breakage in the git build related to the netrc
credentials helper which someone has taken care of in nixpkgs.
The stable channel is not used for anything other than git, so this
should be fine.
Change-Id: I3575a19dab09e1e9556cf8231d717de9890484fb
Adds dottime (as defined on https://dotti.me) as a timestamp format.
This format is designed to simplify working with timestamps across
many different timezones by keeping the timestamp format itself in
UTC (and indicating this with a dot character), but appending the
local offset.
This is implemented as a new format because the timestamp needs to be
rendered both as UTC and including the offset, an implementation using
a strftime formatting string is not sufficient.
