completion: simplify inner 'case' pattern in __gitcomp()

The second '*' in the '--*=*' pattern of the inner 'case' statement of the __gitcomp() helper function never matches anything, so let's use '--*=' instead. The purpose of that inner case statement is to decide when to append a trailing space to the listed options and when not. When an option requires a stuck argument, i.e. '--option=', then the trailing space should not be added, so the user can continue typing the required argument right away. That '--*=*' pattern is supposed to match these options, but for this purpose that second '*' is unnecessary, a '--*=' pattern works just as well. That second '*' would only make a difference in case of a possible completion word like '--option=value', but our completion script never passes such a word to __gitcomp(), because the '--option=' and its 'value' must be completed separately. Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>