Update vendored dependencies

This includes github.com/kurin/blazer 0.2.0, which resolves #1291

vendor/github.com/kurin/blazer/b2/reader.go

@@ -16,13 +16,12 @@ package b2
 
 import (
 	"bytes"
+	"context"
 	"errors"
 	"io"
 	"sync"
 
 	"github.com/kurin/blazer/internal/blog"
-
-	"golang.org/x/net/context"
 )
 
 var errNoMoreContent = errors.New("416: out of content")
@@ -140,11 +139,12 @@ func (r *Reader) thread() {
 				return
 			}
 			rsize, _, _, _ := fr.stats()
-			mr := &meteredReader{r: &fakeSeeker{fr}, size: int(rsize)}
+			mr := &meteredReader{r: noopResetter{fr}, size: int(rsize)}
 			r.smux.Lock()
 			r.smap[chunkID] = mr
 			r.smux.Unlock()
 			i, err := copyContext(r.ctx, buf, mr)
+			fr.Close()
 			r.smux.Lock()
 			r.smap[chunkID] = nil
 			r.smux.Unlock()
@@ -290,11 +290,8 @@ func copyContext(ctx context.Context, dst io.Writer, src io.Reader) (written int
 	return written, err
 }
 
-// fakeSeeker exists so that we can wrap the http response body (an io.Reader
-// but not an io.Seeker) into a meteredReader, which will allow us to keep tabs
-// on how much of the chunk we've read so far.
-type fakeSeeker struct {
+type noopResetter struct {
 	io.Reader
 }
 
-func (fs *fakeSeeker) Seek(int64, int) (int64, error) { return 0, nil }
+func (noopResetter) Reset() error { return nil }