[PATCH 0/9] corrupt object potpourri

I started these patches with the intent of improving clone's behavior on corrupt objects, but my testing uncovered some other nastiness, including two infinite loops in the streaming code!. Yikes.

I think 1-7 are good. We might want to tweak the die() behavior of patch 8, but I think it should come on top. Patch 9 has some pretty ugly performance implications.

At the end of the series, all of the introduced tests pass except for one, which is that "git clone" may silently write out a bogus working tree entry. I haven't tracked that one down yet.

  [1/9]: stream_blob_to_fd: detect errors reading from stream
  [2/9]: check_sha1_signature: check return value from read_istream
  [3/9]: read_istream_filtered: propagate read error from upstream
  [4/9]: avoid infinite loop in read_istream_loose
  [5/9]: add test for streaming corrupt blobs
  [6/9]: streaming_write_entry: propagate streaming errors
  [7/9]: add tests for cloning corrupted repositories
  [8/9]: clone: die on errors from unpack_trees
  [9/9]: clone: run check_everything_connected

-Peff