bug#41139: duplicate service provision error message is too terse

[Ricardo Wurmus]

Ricardo Wurmus <address@hidden> writes:

> This is not very helpful, because it’s hard to tell how we got there.
> Which of the selected services provide xorg-server?

This is the wrong question.  While Shepherd services may have been
introduced to the Shepherd service graph by other general system
services, this kind of information is unavailable when just looking at
the Shepherd service itself.

The only user-facing identifiers a Shepherd service has is its
provisions.  It’s hard to do better without extending Shepherd services
to include provenance information.

-- 
Ricardo