Comment 2 for bug 1719484

From /usr/bin/chromium-browser:

# Set CHROME_VERSION_EXTRA visible in the About dialog and in about:version
if [ "$DIST $RELEASE" = "$BUILD_DIST" ] ; then
  export CHROME_VERSION_EXTRA="$DIST $RELEASE"
else
  export CHROME_VERSION_EXTRA="Built on $BUILD_DIST, running on $DIST $RELEASE"
fi

In most cases the first branch of the if should be true, and the issue would be less visible.

In debian/rules:

    sed -e 's/@BUILD_DIST@/$(DEBIAN_DIST_NAME) $(DEBIAN_DIST_VERSION)/g'

But DEBIAN_DIST_VERSION is not defined anywhere.