debian package build failed after README.md was symlinked to docs/index.md #397

commit
3bca73c

broke debian build

steps to reproduce

mkdir -p -v /opt/diamond
git checkout https://github.com/python-diamond/Diamond.git /opt/diamond
cd /opt/diamond/ 
rm -fv /opt/diamond/build/*.deb 
make deb

Errror returned

copying LICENSE -> /opt/diamond/build/diamond-4.0.380/debian/diamond/usr/share/diamond
error: can't copy 'README.md': doesn't exist or not a regular file
make: *** [install/diamond] Error 1
dpkg-buildpackage: error: fakeroot debian/rules binary gave error exit status 2
debuild: fatal error at line 1364:
dpkg-buildpackage -rfakeroot -D -us -uc -v4.0.380 failed
make: *** [builddeb] Error 29