PyPy 3.5 v6.0.0: inconsistent OpenSSL bindings

So there’s two xenial jobs with PyPy v6.0.0 set up. But tests are behaving inconsistently.

Turns out, that PyPy 2.7 v6.0.0 is linked against OpenSSL 1.1, while

pypy2.7-6.0 is not installed; attempting download
Downloading archive: https://s3.amazonaws.com/travis-python-archives/binaries/ubuntu/16.04/x86_64/pypy2.7-6.0.tar.bz2
$ curl -sSf -o pypy2.7-6.0.tar.bz2 ${archive_url}
$ sudo tar xjf pypy2.7-6.0.tar.bz2 --directory /

$ python --version
Python 2.7.13 (ab0b9caf307db6592905a80b8faffd69b39005b8, Apr 30 2018, 08:21:35)
[PyPy 6.0.0 with GCC 7.2.0]

$ python -c 'import ssl; print("\nOPENSSL_VERSION: " + ssl.OPENSSL_VERSION + "\nOPENSSL_VERSION_INFO: " + repr(ssl.OPENSSL_VERSION_INFO) + "\nOPENSSL_VERSION_NUMBER: " + repr(ssl.OPENSSL_VERSION_NUMBER))'
OPENSSL_VERSION: OpenSSL 1.1.0h 27 Mar 2018
OPENSSL_VERSION_INFO: (1, 1, 0, 8, 15)
OPENSSL_VERSION_NUMBER: 269484175

(https://travis-ci.org/cherrypy/cheroot/jobs/473814367)

pypy3.5-6.0 is not installed; attempting download
Downloading archive: https://s3.amazonaws.com/travis-python-archives/binaries/ubuntu/16.04/x86_64/pypy3.5-6.0.tar.bz2
$ curl -sSf -o pypy3.5-6.0.tar.bz2 ${archive_url}
$ sudo tar xjf pypy3.5-6.0.tar.bz2 --directory /

$ python --version
Python 3.5.3 (fdd60ed87e94, Apr 24 2018, 06:10:04)
[PyPy 6.0.0 with GCC 6.2.0 20160901]

$ python -c 'import ssl; print("\nOPENSSL_VERSION: " + ssl.OPENSSL_VERSION + "\nOPENSSL_VERSION_INFO: " + repr(ssl.OPENSSL_VERSION_INFO) + "\nOPENSSL_VERSION_NUMBER: " + repr(ssl.OPENSSL_VERSION_NUMBER))'
OPENSSL_VERSION: OpenSSL 1.0.1f 6 Jan 2014
OPENSSL_VERSION_INFO: (1, 0, 1, 6, 15)
OPENSSL_VERSION_NUMBER: 268439663

(https://travis-ci.org/cherrypy/cheroot/jobs/473814368)

I think that they both should have the same OpenSSL backend version to avoid inconsistencies and unpleasant side-effects.

cc @BanzaiMan