scripts/check-kernel-fix: improve branch output elimination
    
    ./scripts/check-kernel-fix CVE-2024-26805
    661779e1fcaf ("netlink: Fix kernel-infoleak-after-free in __skb_datagram_iter") merged v6.8-rc7~26^2~35
    Fixes: 1853c9496460 ("netlink, mmap: transform mmap skb into full skb on taps") merged v4.3-rc3~13^2~83
    Security fix for CVE-2024-26805 bsc#1222630 with CVSS 5.5
    ..............................
    ACTION NEEDED!
    SLE15-SP6-RT: MANUAL: backport 661779e1fcafe1b74b3f3fe8e980c1e207fea1fd (Fixes 1853c9496460)
    ALP-current-RT: MANUAL: backport 661779e1fcafe1b74b3f3fe8e980c1e207fea1fd (Fixes 1853c9496460)
    SLE15-SP5-RT: MANUAL: backport 661779e1fcafe1b74b3f3fe8e980c1e207fea1fd (Fixes 1853c9496460)
    SLE12-SP3-TD: MANUAL: backport 661779e1fcafe1b74b3f3fe8e980c1e207fea1fd (Fixes 1853c9496460)
    
    Note how *RT branches are printed even though SLE15-SP6 resp SLE15-SP5
    already have the fix. The current elimination logic only drops branches
    which are in the same state as their merge origin.
    
    mb_line processing is incorrect when that state differs. Fix that by
    looking up the state rather than play with sed and grep for identical
    output.
    
    With this patch applied
    [...]
    ACTION NEEDED!
    SLE12-SP3-TD: MANUAL: backport 661779e1fcafe1b74b3f3fe8e980c1e207fea1fd (Fixes 1853c9496460)