make depcheck.py compatible with stretch

diff --git a/depcheck.py b/depcheck.py
index f1c1a1f..4089ec5 100755 (executable)
--- a/depcheck.py
+++ b/depcheck.py
@@ -245,7 +245,8 @@ class DebianMirror:
         if self.byhash:
             listname = "%s/by-hash/%s/%s" % (os.path.dirname(listname),
                                              self.hashfunc, hashvalue)
-        with requests.get(self.get_uri(listname), stream=True) as resp:
+        with contextlib.closing(requests.get(self.get_uri(listname),
+                                             stream=True)) as resp:
             resp.raise_for_status()
             it = resp.iter_content(65536)
             it = hash_check(it, hashlib.new(self.hashfunc), hashvalue)