Questions and postings pertaining to the development of ImageMagick, feature enhancements, and ImageMagick internals. ImageMagick source code and algorithms are discussed here. Usage questions which are too arcane for the normal user list should also be posted here.
You need libmagick9-dev and not libmagick10-dev (there is no libmagick10-dev).
It's strange to have a different version for the package and the -dev one, but it's correct.
This "problem" is corrected on the new ImageMagick version available at (Debian) experimental, however.