After downloading valentina_0.6.0a-20180212204027_64bit-OSX.dmg and mounting the image, I transferred the .app bundle to /Applications the usual way (dragging to the Applications symlink within the dmg).
When trying to start it, MacOS HighSierra (10.13.3 (17D47)) informed me that the application is corrupt and that I should move it to trash.
When trying to run from the DMG, it advised similarly, only this time it suggested to move the actual dmg to trash.
I've been successfully using earler versions of valentina 0.6 branch. I am currently back on the 2aaffd0 (Tue Jan 23 2018 01:25:26) restored from backups.