Merge #656: Tests: handle offsite URLs that use HTTP/2 with recent versions of curl

3edea72 Tests: handle offsite URLs that use HTTP/2 with recent versions of curl (David A. Harding)

Pull request description:

  While testing #653, I discovered that the `test-binary-availability.sh` test failed locally even though it succeeded on Travis.  The test was looking for HTTP/1.1 success codes but my local `curl` was retrieving the Snapcraft page via HTTP/2 and printing a slightly different success message.  This updates the test to accept either success message.

ACKs for commit 3edea7:

Tree-SHA512: 08bb4032a024839660bcba142a90bc771388702bea9e26ae8b03d8c3d4c3e1cd1bfd17d7bc9a9ea328d11fc731146b82b83d2ad97fa6c3358c35cec4555e8a76

Author: harding

contrib/qa/test-binary-availability.sh

@@ -25,5 +25,5 @@ do
     curl -sI "https://bitcoincore.org${url}"
   else
     curl -sI "$url"
-  fi | grep -q '200 OK' || echo "Error: Could not retrieve $url"
+  fi | egrep -q '(200 OK|HTTP/2 200)' || echo "Error: Could not retrieve $url"
 done | if grep . ; then sed 1iERROR ; false ; else true ; fi