Fix for win32text corrupting files that have CRLF line endings. (issue302)
Also generate a warning when encountering this condition.
From Shun-ichi Goto in attachment win32text-patch3.txt for issue 302.
% 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