Fix build in ELN

See the upstream PR for more information:
https://github.com/osbuild/osbuild-composer/pull/1029

Resolves: rhbz#1884383

osbuild-composer.spec

@@ -15,7 +15,7 @@ As such, it is a drop-in replacement.
 }
 
 Name:           osbuild-composer
-Release:        1%{?dist}
+Release:        2%{?dist}
 Summary:        An image building service based on osbuild
 
 # osbuild-composer doesn't have support for building i686 images
@@ -156,6 +156,8 @@ install -m 0644 -vp test/cloud-init/*                       %{buildroot}%{_datad
 %if 0%{?rhel}
 export GOFLAGS=-mod=vendor
 export GOPATH=$PWD/_build:%{gopath}
+# cd inside GOPATH, otherwise go with GO111MODULE=off ignores vendor directory
+cd $PWD/_build/src/%{goipath}
 %gotest ./...
 %else
 %gocheck