fix pyOpenSSL dependency for py26 in setup.py

setup.py

@@ -9,7 +9,6 @@ def get_install_requires():
     #               openssl-devel libffi-devel
 
     requires = [
-        'pyOpenSSL',
         'python-dateutil',
         'requests',
         'requests-kerberos',
@@ -22,6 +21,13 @@ def get_install_requires():
         # optional auth library for older hubs
         # hubs >= 1.12 are using requests' default GSSAPI
         requires.append('python-krbV')
+    # since pyOpenSSL-18.0.0, py26 support is dropped
+    # see https://pagure.io/koji/issue/1060
+    if sys.version_info[0] == 2 and sys.version_info[1] < 7:
+        requires.append('pyOpenSSL<18.0.0')
+    else:
+        requires.append('pyOpenSSL')
+
     return requires
 
 setup(