Use a simple
  if "substr" in line
before running a regular expression, which saves time,
especially if the regex has a capture group.

This reduces runtime of the check by almost 78 % for me.
Signed-off-by: NJán Tomko <jtomko@redhat.com>
Reviewed-by: NDaniel Henrique Barboza <danielhb413@gmail.com>
Reviewed-by: NErik Skultety <eskultet@redhat.com>