Python3 compatibility: unicode to str

When transitioning from python2 to python3 the following type class
changes occured:

python2 -> python3
unicode -> str
str -> bytes

That means we have to check the python version and do the right type
check python3 will throw an error when it tries to use the unicode
type because it doesn't exist.

Signed-off-by: Jason Wessel <[email protected]>
Signed-off-by: Ben Pfaff <[email protected]>

ovsdb/ovsdb-doc

@@ -65,9 +65,15 @@ def columnGroupToNroff(table, groupXml, documented_columns):
                 if node.hasAttribute('type'):
                     type_string = node.attributes['type'].nodeValue
                     type_json = ovs.json.from_string(str(type_string))
-                    if type(type_json) in (str, unicode):
-                        raise error.Error("%s %s:%s has invalid 'type': %s" 
-                                          % (table.name, name, key, type_json))
+                    # py2 -> py3 means str -> bytes and unicode -> str
+                    try:
+                        if type(type_json) in (str, unicode):
+                            raise error.Error("%s %s:%s has invalid 'type': %s" 
+                                              % (table.name, name, key, type_json))
+                    except:
+                        if type(type_json) in (bytes, str):
+                            raise error.Error("%s %s:%s has invalid 'type': %s" 
+                                              % (table.name, name, key, type_json))
                     type_ = ovs.db.types.BaseType.from_json(type_json)
                 else:
                     type_ = column.type.value