add merge command. means same thing as "update -m".
repo.addchangegroup method now returns number of heads modified and added,
so command line can tell whether update or merge needed. this makes
tiny change to ssh wire protocol, but change is backwards compatible.
pull command now returns 0 if no changes to pull.
%% should show b unknown
? b
%% should show b unknown and c modified
M c
? b
%% should show b added and c modified
M c
A b
%% should show a removed, b added and c modified
M c
A b
R a
%% should show b added and c modified
M c
A b
%% should show b unknown and c modified
M c
? b
%% should show b unknown
? b
%% should show a b and c
a
b
c