goreleaser: Archive contains duplicates of the binary.

Describe the bug

The archive contains multiple copies of the build binary.

To Reproduce

Run goreleaser Run unzip -l [archive.zip] Note multiple copies of binary

# This is an example goreleaser.yaml file with some sane defaults.
# Make sure to check the documentation at http://goreleaser.com
builds:
- env:
  - CGO_ENABLED=0
- goos:
  - darwin
  - freebsd
  - linux
  - openbsd
  - solaris
  - windows
- goarch:
  - 386
  - amd64
  - arm
- ignore:
  - goos: darwin
    goarch: 386
  - goos: darwin
    goarch: arm
archive:
  name_template: "{{ .ProjectName }}_{{ .Version }}_{{ .Os }}_{{ .Arch }}"
  replacements:
    darwin: macOS
    linux: Linux
    windows: Windows
    freebsd: Freebsd
    386: 32-bit
    amd64: 64-bit
    solaris: solaris
  format: zip
checksum:
  name_template: 'checksums.txt'
snapshot:
  name_template: "{{ .Tag }}-next"
changelog:
  sort: asc
  filters:
    exclude:
    - '^docs:'
    - '^test:'

Expected behavior

A single copy of binary contained in [archive.zip]

Environment (please complete the following information):

• OS: mac
• OS version: Darwin kenneth-mac 17.7.0 Darwin Kernel Version 17.7.0: Thu Jun 21 22:53:14 PDT 2018; root:xnu-4570.71.2~1/RELEASE_X86_64 x86_64
• GoReleaser Version: 0.88.0, commit f99940ff5397b099bf606cf1323c00c63afcd153, built at 2018-10-05T02:57:17Z

Additional context