Make CSV import/export compatible across Python versions (also RDBMS journals) (issue 2550976, issue 2550975). The roundup-admin export and import commands are used for migrating between different database backends. It is desirable that they should be usable also for migrations between Python 2 and Python 3, and in some cases (e.g. with the anydbm backend) this may be required. To be usable for such migrations, the format of the generated CSV files needs to be stable, meaning the same as currently used with Python 2. The export process uses repr() to produce the fields in the CSV files and eval() to convert them back to Python data structures. repr() of strings with non-ASCII characters produces different results for Python 2 and Python 3. This patch adds repr_export and eval_import functions to roundup/anypy/strings.py which provide the required operations that are just repr() and eval() in Python 2, but are more complicated in Python 3 to use data representations compatible with Python 2. These functions are then used in the required places for export and import. repr() and eval() are also used in storing the dict of changed values in the journal for the RDBMS backends. It is similarly desirable that the database be compatible between Python 2 and Python 3, so that export and import do not need to be used for a migration between Python versions for non-anydbm back ends. Thus, this patch changes rdbms_common.py in the places involved in storing journals in the database, not just in those involved in import/export. Given this patch, import/export with non-ASCII characters appear based on some limited testing to work across Python versions, and an instance using the sqlite backend appears to be compatible between Python versions without needing import/export, *if* the sessions/otks databases (which use anydbm) are deleted when changing Python version.

def eml_to_mht(db, cl, nodeid, newvalues):
    '''This auditor fires whenever a new file entity is created.

    If the file is of type message/rfc822, we tack onthe extension .eml.

    The reason for this is that Microsoft Internet Explorer will not open
    things with a .eml attachment, as they deem it 'unsafe'. Worse yet,
    they'll just give you an incomprehensible error message. For more 
    information, please see: 

    http://support.microsoft.com/default.aspx?scid=kb;EN-US;825803

    Their suggested work around is (excerpt):

     WORKAROUND

     To work around this behavior, rename the .EML file that the URL
     links to so that it has a .MHT file name extension, and then update
     the URL to reflect the change to the file name. To do this:

     1. In Windows Explorer, locate and then select the .EML file that
        the URL links.
     2. Right-click the .EML file, and then click Rename.
     3. Change the file name so that the .EML file uses a .MHT file name
        extension, and then press ENTER.
     4. Updated the URL that links to the file to reflect the new file
        name extension.

    So... we do that. :)'''
    if newvalues.get('type', '').lower() == "message/rfc822":
        if 'name' not in newvalues:
            newvalues['name'] = 'email.mht'
            return
        name = newvalues['name']
        if name.endswith('.eml'):
            name = name[:-4]
        newvalues['name'] = name + '.mht'

def init(db):
    db.file.audit('create', eml_to_mht)