marc_export should try to avoid exporting broken leaders

[Jason Boyer]

Affects all supported versions of Evergreen

marc_export does not verify that leaders are 24 characters and while many parsers will deal with that as best they can when they hit an end of field character early or late, at least MARC4J (used in discovery layers and other projects) will fall over dead if the leader is too short. While it would ideal to just fix the records, we may as well do what we can when exporting records for use elsewhere (and drop a warning that a record is being modified).

[Jason Boyer (jboyer)]

Here's a branch that adds a --check-leader flag to marc_export: https://git.evergreen-ils.org/?p=working/Evergreen.git;a=shortlog;h=refs/heads/user/jboyer/lp2063350_lead_on / working/user/jboyer/lp2063350_lead_on

When enabled what it will do is discard anything over 24 characters or pad it up to 24 using a template that tries not to be entirely spaces or zeros, and also log a warning that its making a change.