support nested repositories.
mercurial will not recurse into a subdirectory that contains a .hg
directory. it is treated as a separate repository.
adding aadding baNONEXISTENT: No such file or directoryaba: No such file or directoryNONEXISTENT: No such file or directorybaNONEXISTENT: No such file in rev 14467d15ef43ab