fix typo

Author: jblomer

ci/run_unittests.sh

@@ -70,7 +70,7 @@ if [ $CVMFS_UNITTESTS_QUICK = 1 ]; then
 fi
 
 # run the Python unittests for the GeoAPI
-if [ "$CVMFS_GEOAPI_SOURCES" != "x" ]; then
+if [ "x$CVMFS_GEOAPI_SOURCES" != "x" ]; then
   # TODO(jblomer): XML output
   (cd $CVMFS_GEOAPI_SOURCES && python test_cvmfs_geo.py)
 fi