add HGRCPATH env var, list of places to look for hgrc files.
if set, override default hgrc search path.
if empty, only .hg/hgrc of current repo read.
for each element, if directory, all entries in directory with end in
".rc" are added to path. else, element is added to path.
big thing about this change is that user "~/.hgrc" and system hgrc not
longer breaks tests. run-tests makes HGRCPATH empty now.
%% no merges expected
%% merge should fail
abort: 'b' already exists in the working dir and differs from remote
%% merge of b expected
merging for b
merging b
%%
Contents of b should be "this is file b1"
This is file b1
%% merge fails
abort: outstanding uncommited changes
%% merge expected!
merging for b
merging b
%% merge of b should fail
abort: outstanding uncommited changes
%% merge of b expected
merging for b
merging b