ftbfs on non-amd64

The build of the test package fails with:

make[6]: Leaving directory '/tmp/tmp9tnlt7ag/melticecream'
 dpkg-genbuildinfo --build=binary
dpkg-genbuildinfo: error: binary build with no binary artifacts found; .buildinfo is meaningless
dpkg-buildpackage: error: dpkg-genbuildinfo --build=binary gave error exit status 2

Changing the test packages to be arch: all rather than arch: any still leaves test_subsequent_runs_with_new_script failing, with

         self.assertTrue(re.match("Using '{}' directory\nFile '{files}_test.sh already migrated, skipping\nFile '{files}_test.sh already migrated, skipping\n"
                                 "File '{files}_test.sh already migrated, skipping\nExecuting: {}\nExecuting: {}\n".format(self.script_path, os.path.join(self.script_path, '08_test.sh'),
                                                                                                                      os.path.join(self.script_path, '08_testexecute.sh'),
                                                                                                                      files='(01|02|10)'),
                        stdout))

failing to match this output:

Using '/<<BUILDDIR>>/session-migration-0.3.1+ppa4/obj-x86_64-linux-gnu/tests/data/main/session-migration/scripts' directory
File '02_test.sh already migrated, skipping
File '01_test.sh already migrated, skipping
File '10_test.sh already migrated, skipping
Executing: /<<BUILDDIR>>/session-migration-0.3.1+ppa4/obj-x86_64-linux-gnu/tests/data/main/session-migration/scripts/08_test.sh
Executing: /<<BUILDDIR>>/session-migration-0.3.1+ppa4/obj-x86_64-linux-gnu/tests/data/main/session-migration/scripts/08_testexecute.sh

(as an aside, these tests are not written in such a way as to make failures easy to diagnose!)