object-name: iterate ambiguous objects before showing header

object-name: iterate ambiguous objects before showing header

Change the "The candidates are" header that's shown for ambiguous
objects to be shown after we've iterated over all of the objects.

If we get any errors while doing so we don't want to split up the the
header and the list as a result. The two will now be printed together,
as shown in the updated testcase.

As we're accumulating the lines into as "struct strbuf" before
emitting them we need to add a trailing newline to the call in
show_ambiguous_object(). This and the change from "The candidates
are:" to "The candidates are:\n%s" helps to give translators more
context.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>