Rebuild Nightly (#1120)

* Update build.sh

Sets --pre in pip for nightly build.

* Update build.sh

Author: brianjo

.jenkins/build.sh

@@ -13,6 +13,8 @@ sudo apt-get install -y --no-install-recommends unzip p7zip-full sox libsox-dev
 
 export PATH=/opt/conda/bin:$PATH
 rm -rf src
+
+# Allow prerelease in requirements.txt
 pip install -r $DIR/../requirements.txt
 
 # export PATH=/opt/conda/bin:$PATH