hgweb: fix handling of arguments in the between command stable

hgweb: fix handling of arguments in the between command

The 'pairs' argument was coded to be optional, but the code would
crash if it was not provided.

--- a/mercurial/hgweb/protocol.py	Mon Feb 22 23:30:01 2010 -0800
+++ b/mercurial/hgweb/protocol.py	Tue Feb 23 11:34:08 2010 -0500
@@ -62,9 +62,8 @@
     yield resp
 
 def between(repo, req):
-    if 'pairs' in req.form:
-        pairs = [map(bin, p.split("-"))
-                 for p in req.form['pairs'][0].split(" ")]
+    pairs = [map(bin, p.split("-"))
+             for p in req.form['pairs'][0].split(" ")]
     resp = cStringIO.StringIO()
     for b in repo.between(pairs):
         resp.write(" ".join(map(hex, b)) + "\n")