Support for more lines of context in hg merge?

[Daniel Faken]

Hello all,

   I recently encountered a problem where the Hg automerge inserted some 
duplicate code into the file.

   Basically the inputs were like this:

   ..long stretch of identical code..
   ..line A of identical code except for a change in a function name..
   ..two lines of identical code..
   ..line B of identical code except for a change in a function name..
   ..block of identical code..
  ..long stretch of identical code..

   and the result of automerge was that line A and B are merged 
properly, but the 'block of identical code' gets duplicated.

   It appears this is due to some complex revision history [partly 
involving changes to the 'block of identical code'] since the problem 
doesn't occur if I get rid of the history.

   I can't post the code here, but it appears that a similar situation 
is described at 
http://stackoverflow.com/questions/5003577/how-safe-are-automatic-merges-in-mercurial

   In that Stackoverflow discussion it mentions that the _default_ 
context is three lines wide, and I'm thinking that our problems might be 
lessened with more context.  (though i realize we might get more prompts 
for manual merges as well)

   So my question: is there some way to specify an increased number of 
lines to use for context?

   The only option I could find was for the diff tool, but the help 
explicitly says this is only for the diff tool.

thanks for any help!
Daniel Faken