The old code did not work correctly if only a single object Id was to be sent to got-read-pack. Make got-read-pack error out if the list of commits for object enumeration is empty to catch this problem if it occurs again. Found by the send_basic test, which was failing with GOT_TEST_PACK=1 ok tracey

This allows the main process to avoid looping over all object IDs again in case the pack file used for enumeration is complete. ok op@

in this case they're luckily the same; got_imsg_object_idlist and got_imsg_reused_delta only have one size_t long field. ok stsp@

use correct error code and ok stsp@

Simplifies the reading of the author/committer string and makes also the code shorter. ok stsp@

recv_imsg_error already checks the size of the message, and it does so more precisely than the removed code. ok stsp@

The problem that was found in the earlier version has been fixed. ok op@

This implementation marked commits and trees as enumerated before all trees which they depend on were enumerated. This behaviour leads to incomplete pack files when a tree is only partially packed and got-read-pack hits a missing tree entry as a result. The algorithm must be reworked such that packed leave nodes are marked enumerated first, then bubble-up. Found by op@

ok op@

imsg_read() will call recvmsg() on the file descriptor regardless of the read buffer's state, so we should ensure that data is ready. The read buffer is used by imsg_get(), not imsg_read(). We already call imsg_get() before imsg_read(), and call the latter only if imsg_get() returns zero.