Fix regression on agent 5 only

[gzussa]

What does this PR do?

This PR reverts changes made in #2488.
This PR introduced regression with Agent 5.
However we still want these changes in for Agent 6.

Motivation

Fix regression with Agent 5
see #2813

Review checklist

• PR has a meaningful title or PR has the no-changelog label attached
• Feature or bugfix has tests
• Git history is clean
• If PR impacts documentation, docs team has been notified or an issue has been opened on the documentation repo
• If PR adds a configuration option, it has been added to the configuration file.

Additional Notes

Anything else we should know when reviewing?

[olivielpeau]

Code changes LGTM (CI appears to be failing though, haven't looked at why)

Also, out of curiosity: do you have a way to track the "workarounds"/compatibility fixes that we should drop once Agent 5's regular releases stop?

[gzussa]

Require this #2850 for CI to pass

[gzussa]

Unfortunately, we don't have an automated way to track agent version fork logic.
Hopefully, This is something we have been prohibiting by design (as much as we could) to the exception of logic in datadog_check_* modules which we know about.
That being said this kind of logic is always done using a try... except ImportError: so i guess will just grep for that :)

[ofek]

@olivielpeau Grepping for TODO or FIXME is what I do. I haven't compiled a list yet

[codecov-io]

Codecov Report

Merging #2848 into master will increase coverage by 7.52%.
The diff coverage is 80.95%.

@@            Coverage Diff             @@
##           master    #2848      +/-   ##
==========================================
+ Coverage   85.55%   93.07%   +7.52%     
==========================================
  Files         666       11     -655     
  Lines       37292      578   -36714     
  Branches     4438       69    -4369     
==========================================
- Hits        31904      538   -31366     
+ Misses       4078       30    -4048     
+ Partials     1310       10    -1300

[gmmeyer]

lgtm

[olivielpeau]

ok, thanks for the answers! Relying on the TODOs and FIXMEs sounds ok to me as long as we're sure they're there for everything we mean to drop after the last scheduled release of Agent 5 👍