Failed ffmpeg is now noisier

This should be enough to fail the build when the binary doesn't work.

Dockerfile

@@ -204,7 +204,8 @@ RUN set -x && \
 
 # Append software versions
 RUN set -x && \
-  FFMPEG_VERSION=$(/usr/local/bin/ffmpeg -version | head -n 1 | awk '{ print $3 }') && \
+  /usr/local/bin/ffmpeg -version && \
+  FFMPEG_VERSION=$(set -o pipefail ; /usr/local/bin/ffmpeg -version | head -n 1 | awk '{ print $3 }' || exit) && \
   printf -- "ffmpeg_version = '%s'\n" "${FFMPEG_VERSION}" >> /app/common/third_party_versions.py
 
 # Copy root