tests

Add hint how to deal with scmsync-nobranch scenarios #635

Job	Run time
unit - read only fixtures	22s
unit (registry.fedoraproject.org/fedora:38)	53s
unit (registry.fedoraproject.org/fedora:39)	1m 4s
unit (registry.fedoraproject.org/fedora:rawhide)	28s
unit (registry.opensuse.org/opensuse/leap:15.3)	1m 34s
unit (registry.opensuse.org/opensuse/leap:15.4)	1m 26s
unit (registry.opensuse.org/opensuse/leap:15.5)	1m 47s
unit (registry.opensuse.org/opensuse/tumbleweed)	1m 8s
unit (quay.io/centos/centos:stream9)	36s
unit (docker.io/library/debian:stable)	27s
unit (docker.io/library/debian:unstable)	33s
unit (docker.io/library/ubuntu:latest)	29s
behave	4m 35s
	15m 22s

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