'torsion' command buggy

[pett]

The following bug report has been submitted:
Platform:        Darwin-18.7.0-x86_64-i386-64bit
ChimeraX Version: 0.91 (2019-12-02)
Description
"torsion" isn't setting the torsion (like it should), nor is it even changing the torsion by the specifid amount, just changing it seemingly randomly.

Log:
UCSF ChimeraX version: 0.91 (2019-12-02)  
© 2016-2019 Regents of the University of California. All rights reserved.  
How to cite UCSF ChimeraX  

> open 1zik format mmCIF fromDatabase pdb

1zik title:  
GCN4-leucine zipper core mutant ASN16LYS In the dimeric state [more info...]  
  
Chain information for 1zik #1  
---  
Chain | Description  
A B | general control protein GCN4  
  
  

> preset "initial styles" sticks

Preset implemented in Python; no expansion to individual ChimeraX commands
available.  

> help bondrot

No help found for 'bondrot'  

> help torsion

> select /A:17@CA

1 atom, 1 model selected  

> torsion :17@ca,cb,cg,cd1

Must specify exactly 4 atoms for 'torsion' command; you specified 8  

> torsion /a:17@ca,cb,cg,cd1

Torsion angle for atoms /A TYR 17 CA CB CG CD1 is -32.2237°  

> torsion /a:17@ca,cb,cg,cd1 180

> torsion /a:17@ca,cb,cg,cd1 -32.2237

> torsion /a:17@ca,cb,cg,cd1 -32.2237

> torsion /a:17@ca,cb,cg,cd1 -32.2237

> torsion /a:17@ca,cb,cg,cd1 -32.2237

> torsion /a:17@ca,cb,cg,cd1 -32.2237

> torsion /a:17@ca,cb,cg,cd1 -32.2237

> torsion /a:17@ca,cb,cg,cd1 -32.2237

> torsion /a:17@ca,cb,cg,cd1 -32.2237

> torsion /a:17@ca,cb,cg,cd1 -32.2237

> torsion /a:17@ca,cb,cg,cd1 -32.2237

> torsion /a:17@ca,cb,cg,cd1 -32.2237

> torsion /a:17@ca,cb,cg,cd1 -32.2237

> torsion /a:17@ca,cb,cg,cd1 -32.2237

> torsion /a:17@ca,cb,cg,cd1

Torsion angle for atoms /A TYR 17 CA CB CG CD1 is -128.744°  

> torsion /a:17@ca,cb,cg,cd1 -32.2237

> torsion /a:17@ca,cb,cg,cd1

Torsion angle for atoms /A TYR 17 CA CB CG CD1 is 134.736°  




OpenGL version: 4.1 ATI-2.11.21
OpenGL renderer: AMD Radeon Pro 575X OpenGL Engine
OpenGL vendor: ATI Technologies Inc.