Don't abort when backup files already exist. Don't allow alternative names. Rationale: - When the user wants to revert, he shouldn't be stopped from doing this just because some old backups will be overwritten. - To not clobber important files by accident, alternative names for backup files were disabled. As the backup target now has a fixed name, the user doesn't have to be informed about the backup copy (unless --verbose)

%% 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 uncommitted changes
%% merge expected!
merging for b
merging b
%% merge of b should fail
abort: outstanding uncommitted changes
%% merge of b expected
merging for b
merging b