GPG key errors/HTTPS issue for `mail` host

Note that this host is very out of date (14.04)

Total run time:    32.678 s
mail.ams1.psf.io:
----------
          ID: python-requests
    Function: pkg.latest
      Result: False
     Comment: An error was encountered while checking the newest available version of package(s): W: GPG error: http://n
              W: There is no public key available for the following key IDs:
              C631127F87FA12D1
              W: There is no public key available for the following key IDs:
              71DAEAAB4AD4CAB6
              W: There is no public key available for the following key IDs:
              08B3810CB7017B89
              E: Method https has died unexpectedly!
              E: Sub-process https received a segmentation fault.
     Started: 13:26:06.117591
    Duration: 1440.461 ms
     Changes:
----------
          ID: consul-external-console
    Function: consul.external_service
        Name: console
      Result: False
     Comment: One or more requisite failed: base.salt.python-requests
     Started: 13:26:12.510934
    Duration: 0.034 ms
     Changes:
----------
          ID: consul-external-jobs
    Function: consul.external_service
        Name: jobs
      Result: False
     Comment: One or more requisite failed: base.salt.python-requests
     Started: 13:26:12.512919
    Duration: 0.034 ms
     Changes:

Start by inspecting the configuration for mail.ams1.psf.io and the package update represented by the python-requests state. Reproduce the missing GPG key and HTTPS segmentation-fault errors on the reported Ubuntu 14.04 host, then verify that python-requests and the dependent consul services complete successfully.