port -v selfupdate failed on El Capitan

[my@…]

It was good yesterday. But it fails today, yet I have tried many times. Even reinstalling the MacPorts base cannot help.

$ sudo port -v selfupdate
Password:
--->  Updating MacPorts base sources using rsync
receiving file list ... done

sent 36 bytes  received 69 bytes  5.12 bytes/sec
total size is 27013120  speedup is 257267.81
receiving file list ... done

sent 36 bytes  received 76 bytes  7.23 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.