Find the system's MD5 binary.
Different binaries calculate MD5 checksums on different systems. Try
a couple known programs and only calculate and verify the checksum
if they exist. This should silence warnings on eg OpenBSD.
% file replaced with directory
adding a
% should fail - would corrupt dirstate
abort: file named 'a' already in dirstate
% directory replaced with file
adding a/a
% should fail - would corrupt dirstate
abort: directory named 'a' already in dirstate
% directory replaced with file
adding b/c/d
% should fail - would corrupt dirstate
abort: directory named 'b' already in dirstate