What about 1.2.3.x? How does dub handle letters in version numbers?Maybe "1.2.3.0w" would be viable ('w' for 'wrap').
1.2.3.x is an invalid version number. Only 3 group numbers are allowed [1]. Though you could use prerelease and/or build suffixes (1.2.3-0w / 1.2.3+0w).
[1] - www.semver.org