detect if clock skew is probably really time zone misconfiguration

Many times when a tor client has clock skew, it's offset from the network by a round number of hours (or half hours), implying a time zone misconfiguration of some kind. We might want to detect these situations and either automatically compensate, or report a better warning to the user than we do currently.

changed milestone to %Tor: unspecified

added 034-removed-20180328 034-triage-20180328 bootstrap clock-skew component::core tor/tor ex-sponsor-19 ex-sponsor19 milestone::Tor: unspecified priority::medium severity::normal status::new type::enhancement ux labels

Trac:
Cc: N/A to brade, mcs

At least a few instances of this have shown up on IRC where the user had their time zone set to UTC but the clock set to their local time. Multiple consistent clock skew indications that are a round number of hours or half hours combined with a time zone that appears to be UTC should be a strong hint that the time zone is misconfigured.

Trac:
Sponsor: N/A to Sponsor8

Label a bunch of (arguable and definite) enhancements as enhancements for 0.3.4.

Trac:
Milestone: Tor: 0.3.3.x-final to Tor: 0.3.4.x-final

Trac:
Keywords: bootstrap clock-skew ux deleted, bootstrap clock-skew ux s8-errors added

Trac:
Keywords: bootstrap clock-skew ux s8-errors deleted, clock-skew, 034-triage-20180328, ux, s8-errors, bootstrap added

Per our triage process, these tickets are pending removal from 0.3.4.

Trac:
Keywords: N/A deleted, 034-removed-20180328 added

These tickets, tagged with 034-removed-*, are no longer in-scope for 0.3.4. We can reconsider any of them, if time permits.

Trac:
Milestone: Tor: 0.3.4.x-final to Tor: unspecified

Trac:
Cc: brade, mcs to brade, mcs, intrigeri

Marked #27806 (closed) as a duplicate.

Trac:
Keywords: s8-errors deleted, N/A added
Sponsor: Sponsor8 to N/A

Many clock skew issues were already fixed recently by relaxing consensus lifetimes on the client. Remaining issues might be PT-related, so move to sponsor19.

Trac:
Sponsor: N/A to Sponsor19-can

Adding the keyword to mark everything that didn't fit into the time for sponsor 19.

Trac:
Keywords: N/A deleted, ex-sponsor-19 added

Remove sponsor 19 and add a keyword ex-sponsor19 to mark all the tickets that could have been in the scope of the sponsor.

Trac:
Keywords: N/A deleted, ex-sponsor19 added
Sponsor: Sponsor19-can to N/A

mentioned in issue #27806 (closed)

moved to tpo/core/tor#23521 (closed)