Close piped processes on cancellation

internal/git/blob_reader.go

@@ -51,6 +51,9 @@ func (reader *BlobReader) Read(ctx context.Context, objectID string) ([]byte, er
 
 	reader.mu.Lock()
 	defer reader.mu.Unlock()
+	if err := ctx.Err(); err != nil {
+		return nil, fmt.Errorf("read blob %s: %w", objectID, err)
+	}
 	if reader.terminal != nil {
 		return nil, reader.terminal
 	}