pythonPackages.sentry-sdk: Fix the test suite

This package could not build because the tests require /etc/protocols.
Therefore, make this file available using libredirect.

pkgs/development/python-modules/sentry-sdk/default.nix

@@ -1,4 +1,22 @@
-{ stdenv, buildPythonPackage, fetchPypi, isPy3k, urllib3, certifi, django, flask, tornado, bottle, rq, falcon, celery, pyramid, sanic, aiohttp }:
+{ aiohttp
+, bottle
+, buildPythonPackage
+, celery
+, certifi
+, django
+, falcon
+, fetchPypi
+, flask
+, iana-etc
+, isPy3k
+, libredirect
+, pyramid
+, rq
+, sanic
+, stdenv
+, tornado
+, urllib3
+}:
 
 buildPythonPackage rec {
   pname = "sentry-sdk";
@@ -20,4 +38,14 @@ buildPythonPackage rec {
     license = licenses.bsd2;
     maintainers = with maintainers; [ gebner ];
   };
+
+  # The Sentry tests need access to `/etc/protocols` (the tests call
+  # `socket.getprotobyname('tcp')`, which reads from this file). Normally
+  # this path isn't available in the sandbox. Therefore, use libredirect
+  # to make on eavailable from `iana-etc`. This is a test-only operation.
+  preCheck = ''
+    export NIX_REDIRECTS=/etc/protocols=${iana-etc}/etc/protocols
+    export LD_PRELOAD=${libredirect}/lib/libredirect.so
+  '';
+  postCheck = "unset NIX_REDIRECTS LD_PRELOAD";
 }