cmd/go/internal/modcmd: inject modfetch.Fetcher_ into DownloadModule

cmd/go/internal/modcmd: inject modfetch.Fetcher_ into DownloadModule

This commit continues the injection of the global Fetcher_ variable into
the various function calls that make use of it.  The purpose is to
prepare for the eventual removal of the global Fetcher_ variable and
eliminate global state within the modfetch package.

[git-generate]
cd src/cmd/go/internal/modcmd
rf '
 inject modfetch.Fetcher_ DownloadModule
'
cd ../modfetch
rf '
  add downloadZip:/f, err := tempFile.*/+0 _ = f \
    file, err := tempFile(ctx, filepath.Dir(zipfile), filepath.Base(zipfile), 0o666) \
    _ = file
'
rf '
  add downloadZip:/f.Close\(\)/+0 file.Close()
  rm downloadZip:/file.Close\(\)/-1
  add downloadZip:/os.Remove\(f.Name\(\)\)/+0 os.Remove(file.Name())
  rm downloadZip:/os.Remove\(file.Name\(\)\)/-1
'
sed -i '
  s/ f, err := tempFile(ctx, filepath.Dir(zipfile), filepath.Base(zipfile), 0o666)/file, err := tempFile(ctx, filepath.Dir(zipfile), filepath.Base(zipfile), 0o666)/
  s/err := repo.Zip(ctx, f, mod.Version)/err := repo.Zip(ctx, file, mod.Version)/
  s/if _, err := f.Seek(0, io.SeekStart); err != nil {/if _, err := file.Seek(0, io.SeekStart); err != nil {/
  s/if err := f.Truncate(0); err != nil {/if err := file.Truncate(0); err != nil {/
  s/fi, err := f.Stat()/fi, err := file.Stat()/
  s/z, err := zip.NewReader(f, fi.Size())/z, err := zip.NewReader(file, fi.Size())/
  s/for _, f := range z.File {/for _, zf := range z.File {/
  s/if !strings.HasPrefix(f.Name, prefix) {/if !strings.HasPrefix(zf.Name, prefix) {/
  s/return fmt.Errorf("zip for %s has unexpected file %s", prefix\[:len(prefix)-1\], f.Name)/return fmt.Errorf("zip for %s has unexpected file %s", prefix[:len(prefix)-1], zf.Name)/
  s/if err := f.Close(); err != nil {/if err := file.Close(); err != nil {/
  s/if err := hashZip(fetcher_, mod, f.Name(), ziphashfile); err != nil {/if err := hashZip(fetcher_, mod, file.Name(), ziphashfile); err != nil {/
  s/if err := os.Rename(f.Name(), zipfile); err != nil {/if err := os.Rename(file.Name(), zipfile); err != nil {/
' fetch.go
rf '
  rm downloadZip:/_ = file/-3 downloadZip:/_ = file/-2 downloadZip:/file, err := tempFile\(ctx, filepath.Dir\(zipfile\), filepath.Base\(zipfile\), 0o666\)/+1
'
rf '
  mv InfoFile.fetcher_ InfoFile.f
  mv InfoFile Fetcher.InfoFile
  mv GoModFile.fetcher_ GoModFile.f
  mv GoModFile Fetcher.GoModFile
  mv GoModSum.fetcher_ GoModSum.f
  mv GoModSum Fetcher.GoModSum
  mv Download.fetcher_ Download.f
  mv Download Fetcher.Download
  mv download.fetcher_ download.f
  mv download Fetcher.download
  mv DownloadZip.fetcher_ DownloadZip.f
  mv DownloadZip Fetcher.DownloadZip
  mv downloadZip.fetcher_ downloadZip.f
  mv downloadZip Fetcher.downloadZip
  mv checkMod.fetcher_ checkMod.f
  mv checkMod Fetcher.checkMod
  mv hashZip.fetcher_ hashZip.f
'

Change-Id: I1d2e09b8523f5ef2be04b91d858d98fb79c0a771
Reviewed-on: https://go-review.googlesource.com/c/go/+/724242
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Michael Matloob <matloob@google.com>
Reviewed-by: Michael Matloob <matloob@golang.org>