[discourse-web] Allow passing in a specific tagged release out of the tests-passed branch

[Andrea Veri <averi src gnome org>]

commit 01b2068dbee7ac3d4df37d90315953901bdbae4a
Author: Andrea Veri <averi redhat com>
Date:   Fri Dec 6 13:47:01 2019 +0100

    Allow passing in a specific tagged release out of the tests-passed branch

 Dockerfile | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)
---
diff --git a/Dockerfile b/Dockerfile
index 1c2a54c..7dd10bf 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -32,10 +32,12 @@ RUN apt update && \
 ### Set up Discourse ##################################
 #   - So we can overrride it with --build_arg
 ARG DISCOURSE_VERS='tests-passed'
-ENV DISCOURSE_RELEASE=$DISCOURSE_VERS RAILS_ENV=production RAILS_ROOT=/discourse HOME=/discourse
+ARG DISCOURSE_TAGS='v2.4.0.beta8'
+ENV DISCOURSE_RELEASE=$DISCOURSE_VERS DISCOURSE_TAG=$DISCOURSE_TAGS RAILS_ENV=production 
RAILS_ROOT=/discourse HOME=/discourse
 
 RUN mkdir -p discourse && \
-    git clone --depth=1 --single-branch --branch "$DISCOURSE_RELEASE"  
https://github.com/discourse/discourse.git /discourse
+    git clone --depth=1 --single-branch --branch "$DISCOURSE_RELEASE"  
https://github.com/discourse/discourse.git /discourse && \
+    cd /discourse && git checkout tags/$DISCOURSE_TAG
 
 WORKDIR $HOME