Merge branch 'jk/format-patch-ignore-noprefix'

"git format-patch" honors the src/dst prefixes set to nonstandard values with configuration variables like "diff.noprefix", causing receiving end of the patch that expects the standard -p1 format to break. Teach "format-patch" to ignore end-user configuration and always use the standard prefixes. This is a backward compatibility breaking change. * jk/format-patch-ignore-noprefix: rebase: prefer --default-prefix to --{src,dst}-prefix for format-patch format-patch: add format.noprefix option format-patch: do not respect diff.noprefix diff: add --default-prefix option t4013: add tests for diff prefix options diff: factor out src/dst prefix setup