[RCU] Attempt to update plugins failed: Authentication required (git.kolab.org)

I updated the plugins using composer fine on Sunday when upgrading to 1.1.8, but now that I've attempted an upgrade from 1.2.4 I receive this error:

Could not load Structures_Form 0.8.0devel: Invalid version string "0.8.0devel" Could not load Structures_Form_Gtk2 0.8.0devel: Invalid version string "0.8.0devel" Could not load Structures_DataGrid_DataSource_PDO 0.1.1dev1: Invalid version string "0.1.1dev1" Could not load Text_PathNavigator 0.1.0dev2: Invalid version string "0.1.0dev2" Could not load Text_PathNavigator 0.1.0dev1: Invalid version string "0.1.0dev1" Could not load Services_Pingback 0.2.0dev2: Invalid Authentication required (git.kolab.org): Username: Password: Failed to update https://git.kolab.org/diffusion/PNL/php-net_ldap.git,Updating dependencies (including require-dev)

Attempts to visit the https://git.kolab.org/diffusion/PNL/php-net_ldap.git URL directly in a browser yesterday resulted in a 503 error. If I try now, I'm redirected to a Phabricator login page.

Is this a known issue?

Thanks in advance for your feedback.