Security issue: add validation of script names
This patch unifies the search for external script to always go throughutils.FindFile and implements in that function a restriction on validchars in file names and (additionally) that the passed name is the...
Move the hooks file mask into constants.py
This will allow reuse of the same mask for multiple validations.
Signed-off-by: Iustin Pop <iustin@google.com>Reviewed-by: Michael Hanselmann <hansmi@google.com>