Cherry-pick Seastar patch

[nyh]

Backported Seastar commit 4f4e84bb2cec5f11b4742396da7fc40dbb3f162f:

• seastar 04a39f448...06bb98796 (1):

  sstring: refactor to_sstring() using fmt::format_to()

Refs #15127

[scylladb-promoter]

CI state FAILURE - https://jenkins.scylladb.com/job/scylla-5.1/job/scylla-ci/41/

[tchaikov]

 pytest failurea pytest failed:  json_test.py::TestsToJsonSelect::test_basic_data_types

the test failure is expected. but we need to address it on the dtest's end. the change which originally brought the alternative representation of float formatting was https://github.com/scylladb/scylla-dtest/pull/2982. it was more than a refactory. actually it included two kinds of changes:

1. changes which migrated json_test.py from doctest
2. changes for supporting both the new representation.

so we need to backport the whole change to the branch-5.1 branch, so that the test in question can pass before and after this change. yeah, we will drop the old one after this PR lands, like https://github.com/scylladb/scylla-dtest/commit/9c2a868be9e71757dbf596489e6f299f0ecf1899

created at https://github.com/scylladb/scylla-dtest/pull/3620.

EDIT, the PR above got merged. retriggering the build and test 🤞

[scylladb-promoter]

CI state SUCCESS - https://jenkins.scylladb.com/job/scylla-5.1/job/scylla-ci/42/

[nyh]

Reached branch-5.1.
@fruch - dtest now fails - see https://jenkins.scylladb.com/job/scylla-5.1/job/next/325/, can you please take a look?

dtest / json_test.TestsFromJsonInsert.test_basic_data_types
dtest / json_test.TestsToJsonSelect.test_basic_data_types

[tchaikov]

Reached branch-5.1. @fruch - dtest now fails - see https://jenkins.scylladb.com/job/scylla-5.1/job/next/325/, can you please take a look?

dtest / json_test.TestsFromJsonInsert.test_basic_data_types dtest / json_test.TestsToJsonSelect.test_basic_data_types

seems we were using next-5.1 for testing, while the backport went straight into branch-5.1: next-5.1 does not in include the backport.

[nyh]

Reached branch-5.1. @fruch - dtest now fails - see https://jenkins.scylladb.com/job/scylla-5.1/job/next/325/, can you please take a look?
dtest / json_test.TestsFromJsonInsert.test_basic_data_types dtest / json_test.TestsToJsonSelect.test_basic_data_types

seems we were using next-5.1 for testing, while the backport went straight into branch-5.1: next-5.1 does not in include the backport.

Which repository are you referring when you are giving these branch names? This backport in this did not PR go "straight to branch-5.1. It went into scylla.git next-5.1, it wasn't yet promoted to scylla.git's branch-5.1. This is tested against some branch of scylla-dtest.git, I'm not sure which and I want @fruch to take a look at it. It's possible that @fruch's fix didn't make it to scylla-dtest.git's branch-5.1 and this is what Jenkins is using. He may need to do his change in two steps - one that will be able to reach scylla-dtest.git's branch-5.1 (because it passes also on the older version of Scylla, by disabling the test). And only when all the dust settles, a second PR to restore the test.

[tchaikov]

i am referring scylla-dtest repo.

[fruch]

i am referring scylla-dtest repo.

@nyh, @tchaikov is correct I've failed to notice that https://github.com/scylladb/scylla-dtest/pull/3620 is pointed straight at branch-5.1, and not on next-5.1

the code that supposed to warn/block me about those, isn't in 5.1 😩

I'll fix is shortly

[nyh]

This PR reached branch-5.1, and will not be closed automatically, so I'm doing it manually.