Don't do conda update until the channels are correct.

.jenkins/scripts/download_and_install_anaconda.sh

@@ -33,7 +33,6 @@ fi
 echo ${PATH}
 which conda
 conda clean -i -t -y  # in case of corrupt package cache from previous run
-conda update --quiet conda
 # These 2 channels need removing if testing old branches has reinstated them:
 conda config --remove channels http://ssb.stsci.edu/astroconda || :
 conda config --remove channels http://astroconda.gemini.edu/public/noarch || :
@@ -42,4 +41,5 @@ conda config --add channels conda-forge
 conda config --add channels http://jastro.org/astroconda/public
 conda config --set channel_priority true
 conda config --set restore_free_channel false
+conda update --quiet conda
 conda env list