Error message, when host deletion fails because of the maintenance period, collapses multiple spaces.

This makes it impossible to copy the maintenance name and search by it.

Steps to reproduce:

1. Create a host.
2. Create a maintenance entry, include the new host only. Include double space in the name of the maintenance entry - for example "tmp t".
3. Try to delete the host.

Result:
Observe the reported maintenance name having the consecutive spaces collapsed:

Cannot delete host because maintenance "tmp t" must contain at least one host or host group.

Expected:
Consecutive spaces not collapsed.