Merge branch 'jc/send-email-skip-backup'

A careless invocation of "git send-email directory/" after editing 0001-change.patch with an editor often ends up sending both 0001-change.patch and its backup file, 0001-change.patch~, causing embarrassment and a minor confusion. Detect such an input and offer to skip the backup files when sending the patches out. * jc/send-email-skip-backup: send-email: detect and offer to skip backup files