Script brushes: Texture brush strange output

[ihm-tswow]

it just tends to paint a circle at pressure 1.0, and on pressure 2.0 it first draws a circle and then the real shape really hard. Must've messed something really bad

reproduce:

1. make an image 512x512
2. set pressure to 1.0 and try to paint the picture
3. set pressure to 2.0 and try to paint the picture