After performed:

svn update .

at the 'blender_docs' directory, to bringing latest changes in the documentation, if you then run

export LC_ALL=C.UTF-8; export LANG=C.UTF-8; make update_po

you will get this error:

svn: warning: W150002: '/home/htran/blender_documentations/blender_docs/locale/vi' is already under version control
svn: E200009: Could not add all targets because some targets are already versioned
svn: E200009: Illegal target for the requested operation

Error(1) on line 77, in command:
svn add $NEW_DIRS

Makefile:165: recipe for target 'update_po' failed
make: [update_po] Error 1 (ignored)

and it's down to the line above mentioned line of code 'svn add $NEW_DIRS' in the following section of code:

1. note, the Python part filters only for directories
2. there may be a cleaner way to do this in shell.

NEW_DIRS=svn status . | grep -v -e "\.po$" | awk '/^[?]/{print $2}' | python -c "import sys, os; sys.stdout.write('\n'.join([f for f in sys.stdin.read().split('\n') if os.path.isdir(f)]))"
if [ "$NEW_DIRS" != "" ]; then

1. Multiple args, don't quote.

svn add $NEW_DIRS
fi
unset NEW_DIRS

from the file

blender_docs/tools_maintenance/update_po.sh

Printing a few debug lines out and it comes down to the

'locale/<language>'

that was found, but this directory is already under 'svn' control for translation and it has NOTHING to do with manual repository. The following line fixed the problem:

if [ "$NEW_DIRS" != "" && "$NEW_DIRS" != "$LANG" ]; then