OS X compatibility fix

In addition to 50d8c1655f94eeb4421613b45a3b65d24ae089e2.

test/sample/test-sample.sh

@@ -91,6 +91,7 @@ rm obs exp
 echo "    sample.new.t07...\c"
 echo "10" > exp
 $BT sample -i mainFile.bed -n 10 | wc -l > obs
+sed -i 's/^\s*//' obs
 check obs exp
 #rm obs exp