added comment

suggested by Simon Mudd

Signed-off-by: Scott Lanning <[email protected]>

tools/build_version_flags.sh

@@ -17,6 +17,10 @@
 DIR=$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )
 source $DIR/shell_functions.inc
 
+# Normal builds run directly against the git repo, but when packaging (for example with rpms)
+# a tar ball might be used, which will prevent the git metadata from being available.
+# Should this be the case then allow environment variables to be used to source
+# this information instead.
 _build_git_rev=$(git rev-parse --short HEAD)
 if [ -z "$_build_git_rev" ]; then
     _build_git_rev="$BUILD_GIT_REV"