Don't ignore incomplete result.tar files

These usually stem from repeatedly tmpfailing runs where we did not even get as
far as unpacking the source (e. g. repeatedly hitting the ceiling of max
allowed instances/CPUs/etc.). In that case, consider this run a tmpfail result,
instead of ignoring it, as otherwise we end up with that entry being orphaned
in pending.txt.

autopkgtest.py

@@ -309,7 +309,11 @@ class AutoPackageTest(object):
                 (ressrc, ver) = srcver.split()
         except (KeyError, ValueError, tarfile.TarError) as e:
             self.log_error('%s is damaged: %s' % (url, str(e)))
-            return
+            # we can't just ignore this, as it would leave an orphaned request
+            # in pending.txt; consider it tmpfail
+            exitcode = 16
+            ressrc = src
+            ver = None
 
         if src != ressrc:
             self.log_error('%s is a result for package %s, but expected package %s' %
@@ -326,6 +330,9 @@ class AutoPackageTest(object):
         # remove matching test requests, remember triggers
         satisfied_triggers = set()
         for pending_ver, pending_archinfo in self.pending_tests.get(src, {}).copy().items():
+            # if we encounter a tmpfail above, attribute it to the pending test
+            if ver is None:
+                ver = pending_ver
             # don't consider newer requested versions
             if apt_pkg.version_compare(pending_ver, ver) <= 0:
                 try: