IJulia build changing conda channel for some python packages within conda environment

question

#1

When building the IJulia package which is set up to make use of the Conda package and Anaconda most up to date Python 3 installation (with specific sub enviroment ‘conda_jl’ I designated for Julia to be precise), some (8 out of 40 maybe) packages within the sub environment want to be updated through the ‘conda-forge’ channel (no change to the package version numbering whatsoever, only the channel reference).
By the way ‘conda-forge’ channel’s priority for all conda environments is set to the bottom.
IJulia works fine, however when I update the conda_jl environment from time to time with ‘conda update’ the packages get a default update back to prioritized system channel.
IJulia still works fine.
Why would IJulia build process refer to ‘conda-forge’ channel for some packages and reinstall them?