Disallow invalid --pretty= abbreviations
Disallow invalid --pretty= abbreviations

--pretty=o is a valid abbreviation, --pretty=omfg is not

Noticed by: Nicolas Vilz
Signed-off-by: Eric Wong <8c2951295f8292b0c03727bc4652981172298eae@yhbt.net>
Signed-off-by: Junio C Hamano <dc50d1021234060e53ec42a77d526afa2fe07479@cox.net>

destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git