Resulting bundle is missing in some cases

[tim2CF]

Building bundle works locally, but is not working on github ci. I'm building it inside nix docker container anyway, so environment should be completely identical. Command nix-bundle on ci is actually not doing exit with error, but instead of copying result, printing to stdout:

 building '/nix/store/53xbvxhx70sn2ws4nslg6m77mqfanyqb-arx.drv'...
/nix/store/qy9pclnqpmckwa9a297a8jifjkrw357b-arx

And then terminates normally. I do suspect that the reason is this line (probably returns false)

https://github.com/matthewbauer/nix-bundle/blob/223f4ffc4179aa318c34dc873a08cb00090db829/nix-bundle.sh#L57

What can cause this behaviour and how to fix it?