Pinning blas implementation not working?

The documention on pining the blas implementation in https://conda-forge.org/docs/maintainer/knowledge_base.html#switching-blas-implementation doesn't seem to work:

1. run `conda install "liblapack=*=*mkl"`
2. Add `blas=*=mkl` to pinned
3. run `conda update --all` and the blas implementation switch back to netlib:

```
Collecting package metadata (current_repodata.json): done
Solving environment: done

## Package Plan ##

environment location: /opt/miniconda3/envs/blas_issue

The following packages will be downloaded:

package | build
---------------------------|-----------------
_openmp_mutex-4.5 | 1_gnu 22 KB conda-forge
libblas-3.9.0 |1_h86c2bf4_netlib 199 KB conda-forge
libgcc-ng-9.3.0 | h5dbcf3e_17 7.8 MB conda-forge
libgfortran-ng-9.3.0 | he4bcb1c_17 22 KB conda-forge
libgfortran5-9.3.0 | he4bcb1c_17 2.0 MB conda-forge
libgomp-9.3.0 | h5dbcf3e_17 378 KB conda-forge
liblapack-3.9.0 |1_h86c2bf4_netlib 3.0 MB conda-forge
------------------------------------------------------------
Total: 13.3 MB

The following NEW packages will be INSTALLED:

libgcc-ng conda-forge/linux-64::libgcc-ng-9.3.0-h5dbcf3e_17
libgfortran-ng conda-forge/linux-64::libgfortran-ng-9.3.0-he4bcb1c_17
libgfortran5 conda-forge/linux-64::libgfortran5-9.3.0-he4bcb1c_17
libgomp conda-forge/linux-64::libgomp-9.3.0-h5dbcf3e_17

The following packages will be REMOVED:

llvm-openmp-11.0.0-hfc4b9b4_1
mkl-2020.2-256

The following packages will be UPDATED:

_openmp_mutex 4.5-1_llvm --> 4.5-1_gnu
libblas 3.8.0-16_mkl --> 3.9.0-1_h86c2bf4_netlib
liblapack 3.8.0-16_mkl --> 3.9.0-1_h86c2bf4_netlib
```

Environment (conda list):

```
$ conda list
# packages in environment at /opt/miniconda3/envs/blas_issue:
#
# Name Version Build Channel
_libgcc_mutex 0.1 conda_forge conda-forge
_openmp_mutex 4.5 1_llvm conda-forge
blas 1.0 mkl
libblas 3.8.0 16_mkl conda-forge
liblapack 3.8.0 16_mkl conda-forge
llvm-openmp 11.0.0 hfc4b9b4_1 conda-forge
mkl 2020.2 256 conda-forge
```

Details about conda and system ( conda info after step 1):

```
$ conda info
active environment : blas_issue
active env location : /opt/miniconda3/envs/blas_issue
shell level : 2
user config file : /home/eric/.condarc
populated config files : /home/eric/.condarc
conda version : 4.9.0
conda-build version : 3.20.4
python version : 3.7.9.final.0
virtual packages : __cuda=11.1=0
__glibc=2.31=0
__unix=0=0
__archspec=1=x86_64
base environment : /opt/miniconda3 (writable)
channel URLs : https://conda.anaconda.org/conda-forge/linux-64
https://conda.anaconda.org/conda-forge/noarch
https://repo.anaconda.com/pkgs/main/linux-64
https://repo.anaconda.com/pkgs/main/noarch
https://repo.anaconda.com/pkgs/r/linux-64
https://repo.anaconda.com/pkgs/r/noarch
package cache : /opt/miniconda3/pkgs
/home/eric/.conda/pkgs
envs directories : /opt/miniconda3/envs
/home/eric/.conda/envs
platform : linux-64
user-agent : conda/4.9.0 requests/2.24.0 CPython/3.7.9 Linux/5.8.15-201.fc32.x86_64 fedora/32 glibc/2.31
UID:GID : 1000:1000
netrc file : None
offline mode : False

```