System Information
Debian GNU/Linux 8.8 (jessie)
GeForce GTS 250
Blender Version
2.79 (sub 0), branch: master, commit date: 2017-09-11 10:43, hash: 5bd8ac9abfa
Short description of error
Using modal numinput results in an annoying behavior when scene units are not set to "radians" in case you need to specify a rotation angle as the result of acos/asin/atan functions. The result of these functions is implicitely in radians, and when scene units are set to "degrees", returned values are not transformed to degrees, e.g. acos(0.5) returns 1°. To obtain 60° one as to type acos(0.5)*180/pi.
Setting scene units to radians solves the issue but it's somewhat uncomfortable ;-)