fix(internal): properly convert PEP 440 version to SemVer for RCM client [backport #4910 to 1.7] (#4911)

## Description
Backport of #4910

The fix for ensuring RCM used a SemVer compliant version string only
took into account ddtrace versions that match `x.y.zrc2` or
`x.y.zrc2.dev3+gf344hg`, but not `x.y.z.dev3+gf344hg`.

This fix ensures that if we have a `.dev` without `rc` that we properly
convert `.dev` -> `-dev` which will make it SemVer compliant.

Since the tests rely heavily on the version of `ddtrace.__version__`
writing a test is challenging. We should revisit this in the future so
we can mock the version and parametrize the test to ensure all
variations are tested.

## Checklist
- [ ] Followed the [library release note
guidelines](https://ddtrace.readthedocs.io/en/stable/contributing.html#Release-Note-Guidelines)
when writing a release note.
- [ ] Add additional sections for `feat` and `fix` pull requests.
- [ ] [Library
documentation](https://github.com/DataDog/dd-trace-py/tree/1.x/docs)
and/or [Datadog's documentation
site](https://github.com/DataDog/documentation/) is updated. Link to doc
PR in description.

## Reviewer Checklist
- [ ] Title is accurate.
- [ ] Description motivates each change.
- [ ] No unnecessary changes were introduced in this PR.
- [ ] Avoid breaking
[API](https://ddtrace.readthedocs.io/en/stable/versioning.html#interfaces)
changes unless absolutely necessary.
- [ ] Tests provided or description of manual testing performed is
included in the code or PR.
- [ ] Release note has been added and follows the [library release note
guidelines](https://ddtrace.readthedocs.io/en/stable/contributing.html#Release-Note-Guidelines),
or else `changelog/no-changelog` label added.
- [ ] All relevant GitHub issues are correctly linked.
- [ ] Backports are identified and tagged with Mergifyio.

Author: brettlangdon

ddtrace/internal/remoteconfig/client.py

@@ -199,15 +199,33 @@ def __init__(self):
             if container_id is not None:
                 self._headers["Datadog-Container-Id"] = container_id
 
+        # The library uses a PEP 440-compliant versioning scheme, but the
+        # RCM spec requires that we use a SemVer-compliant version.
+        #
+        # However, we may have versions like:
+        #
+        #   - 1.7.1.dev3+gf258c7d9
+        #   - 1.7.1rc2.dev3+gf258c7d9
+        #
+        # Which are not Semver-compliant.
+        #
+        # The easiest fix is to replace the first occurrence of "rc" or
+        # ".dev" with "-rc" or "-dev" to make them compliant.
+        #
+        # Other than X.Y.Z, we are allowed `-<dot separated pre-release>+<build identifier>`
+        # https://semver.org/#backusnaur-form-grammar-for-valid-semver-versions
+        #
+        # e.g. 1.7.1-rc2.dev3+gf258c7d9 is valid
+        tracer_version = ddtrace.__version__
+        if "rc" in tracer_version:
+            tracer_version = tracer_version.replace("rc", "-rc", 1)
+        elif ".dev" in tracer_version:
+            tracer_version = tracer_version.replace(".dev", "-dev", 1)
+
         self._client_tracer = dict(
             runtime_id=runtime.get_runtime_id(),
             language="python",
-            # The library uses a PEP 440-compliant versioning scheme, but the
-            # RCM spec requires that we use a SemVer-compliant version. We only
-            # expect that the first occurrence of "rc" in the version string to
-            # break the SemVer format, so we replace it with "-rc" for
-            # simplicity.
-            tracer_version=ddtrace.__version__.replace("rc", "-rc", 1),
+            tracer_version=tracer_version,
             service=ddtrace.config.service,
             env=ddtrace.config.env,
             app_version=ddtrace.config.version,