Incorrect license detection

[pombredanne]

This, see in https://github.com/foundation/foundation-sites/tree/v6.4.1:

/**
 * Foundation for Sites by ZURB
 * Version 6.4.1
 * foundation.zurb.com
 * Licensed under MIT Open Source
 */
/*! normalize-scss | MIT/GPLv2 License | bit.ly/normalize-scss */

This is reported as two matches of mit AND another of gpl-2.0

        license_detections:
            -   license_expression: mit AND gpl-2.0
                detection_log:
                    - not-combined
                matches:
                    -   score: '100.0'
                        start_line: 5
                        end_line: 5
                        matched_length: 3
                        match_coverage: '100.0'
                        matcher: 2-aho
                        license_expression: mit
                        rule_identifier: mit_172.RULE
                        rule_url: https://github.com/nexB/scancode-toolkit/tree/develop/src/licensedcode/data/rules/mit_172.RULE
                        matched_text: Licensed under MIT
                    -   score: '100.0'
                        start_line: 7
                        end_line: 7
                        matched_length: 2
                        match_coverage: '100.0'
                        matcher: 2-aho
                        license_expression: gpl-2.0
                        rule_identifier: gpl-2.0_818.RULE
                        rule_url: https://github.com/nexB/scancode-toolkit/tree/develop/src/licensedcode/data/rules/gpl-2.0_818.RULE
                        matched_text: GPLv2 License |

but we should have instead detected mit AND mit OR gpl-2.0 and reported a top level expression of mit OR gpl-2.0