[PATCH] t5500.43: make the check a bit more robust

From: Johannes Schindelin <johannes.schindelin@gmx.de>

In 2b695ecd74d (t5500: count objects through stderr, not trace, 2020-05-06) we tried to ensure that the "Total 3" message could be grepped in Git's output, even if it sometimes got chopped up into multiple lines in the trace machinery.

However, the first instance where this mattered now goes through the sideband machinery, where it is _still_ possible for messages to get chopped up.

Note: we have code in `demultiplex_sideband()` _specifically_ to stitch
back together lines that were delivered in separate sideband packets.
However, this stitching fails when a primary packet is delivered in
between the two sideband packets: since a primary packet was received,
`demultiplex_sideband()` has to return that (and cannot wait for other
sideband packets, and therefore has to flush any incomplete line it
received).

This seems only to happen occasionally in the `vs-test` part of our CI builds, i.e. with binaries built using Visual C, but not when building with GCC or clang; The symptom is that t5500.43 fails to find a line matching `remote: Total 3` in the `log` file, which ends in something along these lines:

	remote: Tota
	remote: l 3 (delta 0), reused 0 (delta 0), pack-reused 0

To work around that, use some `sed` magic to re-stitch together those split lines, after the fact.

The other test case touched by 2b695ecd74d (t5500: count objects through stderr, not trace, 2020-05-06) is not affected by this issue because the sideband machinery is not involved there.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
    Work around flakiness in t5500.43
    
    It seems that this test became flaky only recently, although I have to
    admit that I have no idea why: the involved code does not seem to have
    changed recently at all. It should have been fixed by 
    https://lore.kernel.org/git/20200506220741.71021-1-jonathantanmy@google.com/
    , but apparently wasn't completely fixed, despite what I said in that
    thread.

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-753%2Fdscho%2Funflake-t5500.43-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-753/dscho/unflake-t5500.43-v1
Pull-Request: https://github.com/gitgitgadget/git/pull/753

 t/t5500-fetch-pack.sh | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)