tests: avoid time-dependent rebuild of caches

The tests changes the sources.list and the modification time of this
file is considered while figuring out if the cache can be good. Usually
this isn't an issue, but in that case we have the cache generation
produce warnings which appear twice in this case.

Gbp-Dch: Ignore

test/integration/test-apt-acquire-additional-files-duplicates

@@ -48,6 +48,8 @@ ${APTLISTS}/example.org_debian_dists_stable_rocks_i18n_Translation-en" aptget in
 cat >> rootdir/etc/apt/sources.list <<EOF
 deb http://example.org/debian stable main rocks
 EOF
+rm -r rootdir/var/cache/apt/*.bin
+testwarning aptcache gencaches
 testwarningequal "${APTLISTS}/example.org_debian_dists_stable_main_source_Sources
 ${APTLISTS}/example.org_debian_dists_stable_rocks_source_Sources
 ${APTLISTS}/example.org_debian_dists_stable_main_binary-amd64_Packages
@@ -71,6 +73,8 @@ cat >> rootdir/etc/apt/sources.list <<EOF
 deb [target=Contents1,Contents2,Contentsflat arch=amd64] http://example.org/debian stable main rocks
 deb-src [target=Contents1,Contents2,Contentsflat arch=amd64] http://example.org/debian stable main rocks
 EOF
+rm -r rootdir/var/cache/apt/*.bin
+testwarning aptcache gencaches
 testwarningequal "${APTLISTS}/example.org_debian_dists_stable_main_source_Sources
 ${APTLISTS}/example.org_debian_dists_stable_rocks_source_Sources
 ${APTLISTS}/example.org_debian_dists_stable_main_binary-amd64_Packages