self update fails on ElCap: Failed to verify signature for MacPorts source

[permezel@…]

Some port failed (can't remember which -- that was days ago, but I think it had something to do with lua and/or wireshark, so I removed and re-installed, and it was still broke).

So today I decided to try and self update. that failed. So I re-downloaded the ElCap version, and reinstalled. Still fails.

lust# port -v selfupdate
--->  Updating MacPorts base sources using rsync
receiving file list ... done

sent 36 bytes  received 69 bytes  42.00 bytes/sec
total size is 27013120  speedup is 257267.81
receiving file list ... done

sent 36 bytes  received 76 bytes  44.80 bytes/sec
total size is 512  speedup is 4.57
Error: Failed to verify signature for MacPorts source!
To report a bug, follow the instructions in the guide:
    http://guide.macports.org/#project.tickets
Error: /opt/local/bin/port: port selfupdate failed: Failed to verify signature for MacPorts source!

[ryandesign (Ryan Carsten Schmidt)]

Duplicate of #49233.