It interesting. So I downloaded the import template, cleaned it up as per instructions and tried importing that same template, first without changing any of detected import file properties - they all seem OK. I confirmed default field mappings, did not choose any fields for check for duplicates and clicked Import now.
Boom, error:
WARNING: [2] Declaration of SugarFieldMultienum::displayFromFunc($displayType, $parentFieldArray, $vardef, $displayParams, $tabindex) should be compatible with SugarFieldEnum::displayFromFunc($displayType, $parentFieldArray, $vardef, $displayParams, $tabindex = 0) on line 124 in file /home/meldooco/public_html/include/SugarFields/Fields/Multienum/SugarFieldMultienum.php