fix: Prevent unnecessary retries when checking repository existence b…

[AakashSuresh2003]

…y updating GetNonSuccessAsync to retry only on transient 5xx errors, skip deterministic statuses (200/404/301/4xx), add full test coverage, and ensure DoesRepoExist makes a single API call for expected responses. (#1447)

• Did you write/update appropriate tests
• Release notes updated (if appropriate)
• Appropriate logging output
• Issue linked
• Docs updated (or issue created)
• New package licenses are added to ThirdPartyNotices.txt (if applicable)

[Copilot]

Pull request overview

This PR fixes an issue where repository existence checks would retry unnecessarily on deterministic HTTP responses (200/404/301/4xx), causing delays during migrations. The fix updates GetNonSuccessAsync to use a selective retry strategy that only retries on transient server errors (5xx status codes) rather than retrying on all exceptions.

Key Changes

• Modified GetNonSuccessAsync in GithubClient.cs to use HttpRetry with a predicate that filters for 5xx errors only
• Added comprehensive test coverage for expected status codes (404), unexpected success (200), server errors with retry (5xx), and redirect status (301)
• Updated release notes to describe the fix in user-friendly terms

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
src/Octoshift/Services/GithubClient.cs	Replaced generic retry logic with selective HTTP retry that only retries on 5xx status codes, ensuring deterministic responses (200/404/301/4xx) return immediately
src/OctoshiftCLI.Tests/Octoshift/Services/GithubClientTests.cs	Added four new test cases covering expected status, unexpected success, server error retry behavior, and redirect handling; replaced old retry test with comprehensive coverage
RELEASENOTES.md	Added user-friendly description of the fix explaining improved behavior for repository existence checks

[github-actions]

Unit Test Results

  1 files    1 suites   10m 25s ⏱️
975 tests 975 ✅ 0 💤 0 ❌
976 runs  976 ✅ 0 💤 0 ❌

Results for commit abd14ab.

♻️ This comment has been updated with latest results.

[github-actions]

Package	Line Rate	Branch Rate	Complexity	Health
ado2gh	72%	70%	718	➖
Octoshift	83%	73%	1749	✔
bbs2gh	83%	78%	663	✔
gei	80%	71%	574	✔
Summary	81% (7762 / 9641)	73% (1847 / 2533)	3704	✔

[brianaj]

closing in favor of #1487

[brianaj]

@AakashSuresh2003 I am going to hold off on shipping this, I have some concerns with this failing fast for 429s and possible other non-5** that we should retry.