Merge branch 'jk/mbox-from-line' into maint

Some MUAs mangled a line in a message that begins with "From " to ">From " when writing to a mailbox file and feeding such an input to "git am" used to lose such a line. * jk/mbox-from-line: mailinfo: work around -Wstring-plus-int warning mailinfo: make ">From" in-body header check more robust