Add a sed_unterminated_s rule

thefuck/rules/sed_unterminated_s.py

@@ -0,0 +1,17 @@
+import shlex
+from thefuck.utils import quote
+
+
+def match(command, settings):
+    return ('sed' in command.script
+            and "unterminated `s' command" in command.stderr)
+
+
+def get_new_command(command, settings):
+    script = shlex.split(command.script)
+
+    for (i, e) in enumerate(script):
+        if e.startswith(('s/', '-es/')) and e[-1] != '/':
+            script[i] += '/'
+
+    return ' '.join(map(quote, script))