Update the pointer of Continuation's headerBuffer after copying the payload

[CoolTomatos]

This pull request fixes HTTPCORE-772

[ok2c]

@CoolTomatos There are style violations that need to be fixed.

Ideally it would be nice to have a test case for this defect added to TestAbstractH2StreamMultiplexer but I will accept the PR without it.

[CoolTomatos]

Hi @ok2c, thanks for the reply.
Just pushed a commit to fix the style issue.
Will try to add some test coverage tomorrow. Was looking at APIs how to setup some header frames and continuation frames for the test case.

[CoolTomatos]

Hi @ok2c added a small test case that would fail without my fix and passes with my fix. Please have a look!

[ok2c]

@CoolTomatos cherry-picked to 5.3.x

[CoolTomatos]

@CoolTomatos cherry-picked to 5.3.x

Hi @ok2c do we have a rough timeline when 5.3.2 will be released?

[ok2c]

@CoolTomatos It is a nasty one but not severe enough for an emergency release in my opinion. I would release 5.3.2 sometime in January.