Allow --diff on UTF-8 encoded files and templates

lib/ansible/utils/__init__.py

@@ -706,6 +706,13 @@ def make_sudo_cmd(sudo_user, executable, cmd):
         prompt, sudo_user, executable or '$SHELL', pipes.quote(cmd))
     return ('/bin/sh -c ' + pipes.quote(sudocmd), prompt)
 
+_TO_UNICODE_TYPES = (unicode, type(None))
+
+def to_unicode(value):
+    if isinstance(value, _TO_UNICODE_TYPES):
+        return value
+    return value.decode("utf-8")
+
 def get_diff(diff):
     # called by --diff usage in playbook and runner via callbacks
     # include names in diffs 'before' and 'after' and do diff -U 10
@@ -731,10 +738,10 @@ def get_diff(diff):
                     after_header = "after: %s" % diff['after_header']
                 else:
                     after_header = 'after'
-                differ = difflib.unified_diff(diff['before'].splitlines(True), diff['after'].splitlines(True), before_header, after_header, '', '', 10)
+                differ = difflib.unified_diff(to_unicode(diff['before']).splitlines(True), to_unicode(diff['after']).splitlines(True), before_header, after_header, '', '', 10)
                 for line in list(differ):
                     ret.append(line)
-            return "".join(ret)
+            return u"".join(ret)
     except UnicodeDecodeError:
         return ">> the files are different, but the diff library cannot compare unicode strings"