fix errors with latest flake8 (#710)

* fix errors with latest flake8

* Also fix the macOS builds

* fix?

* allow urllib3 to fail for now
diff --git a/.travis.yml b/.travis.yml
index d03d6f8..c76dc45 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -88,19 +88,23 @@
   - env: TOXENV=py35-cryptographyMaster
   - env: TOXENV=py36-cryptographyMaster
   - env: TOXENV=pypy-cryptographyMaster
+  # TODO: undo this once upstream fixes their tests
+  - python: "3.5"
+    env: TOXENV=py35-urllib3Master
+
 
 install:
   - |
     if [[ "$(uname -s)" == 'Darwin' ]]; then
       brew update
       if [[ "${OPENSSL}" == "1.1.0" ]]; then
-        brew install openssl@1.1
+        brew upgrade openssl@1.1
       else
         brew upgrade openssl
       fi
       curl -O https://bootstrap.pypa.io/get-pip.py
       python get-pip.py --user
-      pip install --user virtualenv
+      python -m pip install --user virtualenv
     else
       # install our own pypy. This can be removed if and when Travis gets a reasonably up to date pypy
       if [[ "${TOXENV}" = pypy* ]]; then
diff --git a/examples/simple/server.py b/examples/simple/server.py
index 9cce9e0..d25feb1 100644
--- a/examples/simple/server.py
+++ b/examples/simple/server.py
@@ -73,7 +73,7 @@
         r, w, _ = select.select(
             [server] + list(clients.keys()), list(writers.keys()), []
         )
-    except:
+    except Exception:
         break
 
     for cli in r:
diff --git a/src/OpenSSL/SSL.py b/src/OpenSSL/SSL.py
index 75d080a..667131b 100644
--- a/src/OpenSSL/SSL.py
+++ b/src/OpenSSL/SSL.py
@@ -307,10 +307,10 @@
                 instr = _ffi.buffer(in_, inlen)[:]
                 protolist = []
                 while instr:
-                    l = indexbytes(instr, 0)
-                    proto = instr[1:l + 1]
+                    length = indexbytes(instr, 0)
+                    proto = instr[1:length + 1]
                     protolist.append(proto)
-                    instr = instr[l + 1:]
+                    instr = instr[length + 1:]
 
                 # Call the callback
                 outstr = callback(conn, protolist)
@@ -1080,7 +1080,7 @@
                 if not push_result:
                     _lib.X509_NAME_free(copy)
                     _raise_current_error()
-        except:
+        except Exception:
             _lib.sk_X509_NAME_free(name_stack)
             raise
 
diff --git a/tests/test_crypto.py b/tests/test_crypto.py
index 22a5c88..5642120 100644
--- a/tests/test_crypto.py
+++ b/tests/test_crypto.py
@@ -1846,11 +1846,11 @@
         cert = X509()
         name = cert.get_subject()
         name.C = 'AU'
-        name.O = 'Unit Tests'
+        name.OU = 'Unit Tests'
         cert.set_subject(name)
         assert (
             cert.get_subject().get_components() ==
-            [(b'C', b'AU'), (b'O', b'Unit Tests')])
+            [(b'C', b'AU'), (b'OU', b'Unit Tests')])
 
     def test_get_issuer(self):
         """
@@ -1882,11 +1882,11 @@
         cert = X509()
         name = cert.get_issuer()
         name.C = 'AU'
-        name.O = 'Unit Tests'
+        name.OU = 'Unit Tests'
         cert.set_issuer(name)
         assert (
             cert.get_issuer().get_components() ==
-            [(b'C', b'AU'), (b'O', b'Unit Tests')])
+            [(b'C', b'AU'), (b'OU', b'Unit Tests')])
 
     def test_get_pubkey_uninitialized(self):
         """