rebase-i: explicitly accept tab as separator in commands

The git-rebase-todo is parsed several times with different parsers. In principle, the user input is normalized by transform_todo_ids and further parsing can be stricter. In case the user wrote pick deadbeef<TAB>commit message the parser of transform_todo_ids was considering the sha1 to be "deadbeef<TAB>commit", and was leaving the tab in the transformed sheet. In practice, this went unnoticed since the actual command interpretation was done later in do_next which did accept the tab as a separator. Make it explicit in the code of transform_todo_ids that tabs are accepted. This way, code that mimicks it will also accept tabs as separator. A similar construct appears in skip_unnecessary_picks, but this one comes after transform_todo_ids, hence reads the normalized format, so it needs not be changed. Signed-off-by: Matthieu Moy <Matthieu.Moy@imag.fr> Signed-off-by: Junio C Hamano <gitster@pobox.com>