diff - Odd behavior of opton --ignore-matching-lines

[Jari Aalto]

Test under Bash:

    echo -e "1 2\n1" > a
    echo -e "2 3\n4" > b
    diff -u -I '2' a b

    =>

    -1 2
    -1
    +2 3
    +4

Isn't --ignore-matching-lines supposed to ignore all lines matching REGEXP
"2" above?

Jari