sopel.run: document why Pachuco's cleanup was left out

A few commits back, the commit adding the "restart" command originally
tried to do some cleanup, too. It was left out of the final version of
PR sopel-irc#1333 due to breaking the use of ^C to quit Sopel interactively.

These TODO comments will serve as a reminder to eventually figure out
why the hell shit broke from something that should be simple, like
replacing os._exit() calls (not a great habit) with return values.
Something that shouldn't cause any change in function, but somehow did.

sopel/__init__.py

@@ -102,6 +102,11 @@ def signal_handler(sig, frame):
             logfile.write(trace)
             logfile.write('----------------------------------------\n\n')
             logfile.close()
+            # TODO: This should be handled in run_script
+            # All we should need here is a return value, but replacing the
+            # os._exit() call below (at the end) broke ^C.
+            # This one is much harder to test, so until that one's sorted it
+            # isn't worth the risk of trying to remove this one.
             os.unlink(pid_file)
             os._exit(1)
 
@@ -113,5 +118,8 @@ def signal_handler(sig, frame):
             break
         stderr('Warning: Disconnected. Reconnecting in %s seconds...' % delay)
         time.sleep(delay)
+    # TODO: This should be handled in run_script
+    # All we should need here is a return value, but making this
+    # a return makes Sopel hang on ^C after it says "Closed!"
     os.unlink(pid_file)
     os._exit(0)