build: do not crash if SVN URL pre-validation fails; log error
build: do not crash if SVN URL pre-validation fails; log error

This is the problem:
https://jenkins.debian.net/job/reproducible_fdroid_build_apps/704/console

f-droid/fdroid-server,f-droid/fdroidserver,fdroidtravis/fdroidserver,f-droid/fdroidserver,fdroidtravis/fdroidserver,f-droid/fdroid-server,fdroidtravis/fdroidserver,f-droid/fdroid-server,f-droid/fdroidserver,f-droid/fdroidserver,fdroidtravis/fdroidserver,f-droid/fdroid-server,f-droid/fdroid-server,f-droid/fdroidserver