add more informative error messages to git-mktag
add more informative error messages to git-mktag

Signed-off-by: Björn Engelmann <a3ce878f7231b4ad760ee0db9bc50ca5686c67e3@gmx.de>
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