Gamma conversion in Colormath, Lab to RGB

Question

I'm trying to convert Lab colors to RGB WITHOUT gamma correction (or with gamma = 1). I use the colormath module from within Blender. https://python-colormath.readthedocs.io/en/latest/# It seems to ignore my gamma setting. The conversion is right otherwise (I verified it step by step in Excel using Bruce Lindblooms wisdom http://www.brucelindbloom.com/index.html?Eqn_RGB_XYZ_Matrix.html
Essentially, I need to skip gamma companding, or set the gamma factor to 1.

colormath always returns gamma corrected values, no matter how I set rgb_gamma. I suspect that I'm using the rgb_gamma function wrong, but I can't figure out how to do it right.

from colormath import color_objects

from colormath import color_constants
from colormath import density
from colormath.color_conversions import convert_color
from colormath.color_objects import (
    LabColor,
    sRGBColor,
    XYZColor,
)

#77,82  17,56   7,85 input
#0,800  0,456   0,449 sRGB no gamma, calculated in Excel
#0,906  0,706   0,700 gamma corr. 

BRlab=LabColor(77.82,17.56,7.85, observer='2', illuminant = 'c')
print(BRlab)

BRxyz=convert_color(BRlab, XYZColor, target_illuminant = 'c')
print(BRxyz)

BRxyz.set_illuminant('c')
BRxyz.set_observer('2')
BRxyz.apply_adaptation(target_illuminant = 'd65', adaptation = 'bradford')
print(BRxyz)

BRrgb=convert_color(BRxyz, sRGBColor, target_illuminant = 'd65')
BRrgb.rgb_gamma=1.0  #this setting seems to be ignored 
print("gamma = " , BRrgb.rgb_gamma)
print(BRrgb)
BRrgb.rgb_gamma=2.0 #this setting seems to be ignored, same output no matter if gamma = 1 or gamma = 2
print("gamma = ", BRrgb.rgb_gamma)
print(BRrgb)

print("\n")