allow multiples hook
suggested by Vadim Gelfer
This patch allows to have multiple hooks of the same kind:
for example
commit.email = /my/email/hook
commit.autobuild = /my/build/hook
%% no merges expected
%% merge of b expected
merging for b
merging b
%%
Contents of b should be "this is file b1"
This is file b1
%% merge expected!
merging for b
merging b
%% merge of b expected
merging for b
merging b