do not request files if we expect an IMS hit

If we have a file on disk and the hashes are the same in the new Release
file and the old one we have on disk we know that if we ask the server
for the file, we will at best get an IMS hit – at worse the server
doesn't support this and sends us the (unchanged) file and we have to
run all our checks on it again for nothing. So, we can save ourselves
(and the servers) some unneeded requests if we figure this out on our
own.

1 files changed, 20 insertions, 5 deletions

diff --git a/test/integration/test-apt-update-file b/test/integration/test-apt-update-file
index 665f94fa5..94b604f0e 100755
--- a/test/integration/test-apt-update-file
+++ b/test/integration/test-apt-update-file
@@ -26,14 +26,29 @@ testsuccess aptget update
 # the release files aren't an IMS-hit, but the indexes are
 redatereleasefiles '+1 hour'
 
+# we don't download the index if it isn't updated
 testsuccess aptget update -o Debug::pkgAcquire::Auth=1
+# file:/ isn't shown in the log, so see if it was downloaded anyhow
 cp -a rootdir/tmp/testsuccess.output rootdir/tmp/update.output
+canary="SHA512:$(bzcat aptarchive/dists/unstable/main/binary-amd64/Packages.bz2 | sha512sum |cut -f1 -d' ')"
+testfailure grep -- "$canary" rootdir/tmp/update.output
+
+testfoo() {
+	# foo is still available
+	testsuccess aptget install -s foo
+	testsuccess aptcache showsrc foo
+	testsuccess aptget source foo --print-uris
+}
+testfoo
+
+# the release file is new again, the index still isn't, but it is somehow gone now from disk
+redatereleasefiles '+2 hour'
+find rootdir/var/lib/apt/lists -name '*_Packages*' -delete
 
-# ensure that the hash of the uncompressed file was verified even on a local ims hit
+testsuccess aptget update -o Debug::pkgAcquire::Auth=1
+# file:/ isn't shown in the log, so see if it was downloaded anyhow
+cp -a rootdir/tmp/testsuccess.output rootdir/tmp/update.output
 canary="SHA512:$(bzcat aptarchive/dists/unstable/main/binary-amd64/Packages.bz2 | sha512sum |cut -f1 -d' ')"
 testsuccess grep -- "$canary" rootdir/tmp/update.output
 
-# foo is still available
-testsuccess aptget install -s foo
-testsuccess aptcache showsrc foo
-testsuccess aptget source foo --print-uris
+testfoo