[mhonarc] seek when needed and add some comments

[Olav Vitters <ovitters src gnome org>]

commit d6945a67b08c7a20f3cc98531a7fd39360797d52
Author: Olav Vitters <olav vitters nl>
Date:   Wed Feb 13 13:36:11 2013 +0100

    seek when needed and add some comments

 archive.py |    7 +++++--
 1 files changed, 5 insertions(+), 2 deletions(-)
---
diff --git a/archive.py b/archive.py
index 3569ebe..448d6ea 100755
--- a/archive.py
+++ b/archive.py
@@ -115,6 +115,7 @@ class Archiver:
 
     def determine_received_time(self, fd):
         """Determines the received time of a message"""
+        fd.seek(0)
         msg = email.message_from_file(fd)
         received_texts = msg.get_all('received')
         if received_texts is None:
@@ -196,10 +197,9 @@ class Archiver:
                     sys.stdout.write(line)
 
                     if msg.tell():
-                        msg.seek(0)
-
                         archivepath = self.handle_message(msg, newmsgs, archivepath)
 
+                        # msg has been handled, clear it for the next
                         msg.seek(0)
                         msg.truncate(0)
                 else:
@@ -207,9 +207,12 @@ class Archiver:
 
                 msg.write(line)
 
+            # End of file: handle existing message, if any
             if msg.tell():
                 archivepath = self.handle_message(msg, newmsgs, archivepath)
 
+        # If archivepath is set, likely a message has been archived
+        # in which case the index has to be updated
         if archivepath:
             Archiver.make_index(self.listname, self.private)