[meld] Add comment explaining the heuristic constant for discarded lines

[Kai Willadsen <kaiw src gnome org>]

commit cdbb29f6dca4754e127b8f6ce5423daea514dbd0
Author: Kai Willadsen <kai willadsen gmail com>
Date:   Fri Feb 26 09:19:37 2010 +1000

    Add comment explaining the heuristic constant for discarded lines

 meld/matchers.py |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/meld/matchers.py b/meld/matchers.py
index 52375ef..fb81c24 100644
--- a/meld/matchers.py
+++ b/meld/matchers.py
@@ -115,6 +115,8 @@ class MyersSequenceMatcher(difflib.SequenceMatcher):
                     a2.append(a[i])
                     aindex[k] = i
                     k += 1
+            # We only use the optimised result if it's worthwhile. The constant
+            # represents a heuristic of how many lines constitute 'worthwhile'.
             self.lines_discarded = m - j > 10 or n - k > 10
             if self.lines_discarded:
                 a = a2