track FileNotFoundException if a concurrent thread delete the file before locking and try recreate it

git-svn-id: https://svn.apache.org/repos/asf/archiva/trunk@1550647 13f79535-47bb-0310-9956-ffa450edef68
try creating the file before the lock

git-svn-id: https://svn.apache.org/repos/asf/archiva/trunk@1550648 13f79535-47bb-0310-9956-ffa450edef68