v8.0.0a16

[integration]

*tests

CHANGE: (#5900) use dirac-login instead of dirac-proxy-init for tests

*FrameworkSystem

NEW: (#5899) dirac-login (AS) added VOMS extension
NEW: (#5896) dirac-login try to connect to DIRAC AS if no local certificate

*Core

FIX: (#5898) print error details/callstack in BaseRequestHandler