Don't pull avatar if remote GitHub Enterprise uses private mode.

[Vlatombe]

Description

When defining a GitHub organization pointing at a Github Enterprise instance running in private mode, the avatar URL can't be accessed directly. This is causing a broken icon to be displayed as well as layout problems in list view in recent Jenkins versions.

This patch detects if the remote instance is in private mode and fallbacks to the standard github icon in that case.
The organization folder needs to be saved after upgrading to apply the new logic.

Before

After

Submitter checklist

• Link to JIRA ticket in description, if appropriate.
• Change is code complete and matches issue description
• Automated tests have been added to exercise the changes
• Reviewer's manual test instructions provided in PR description. See Reviewer's first task below.

Reviewer checklist

• Run the changes and verify that the change matches the issue description
• Reviewed the code
• Verified that the appropriate tests have been written or valid explanation given

Documentation changes

• Link to jenkins.io PR, or an explanation for why no doc changes are needed

Users/aliases to notify

[jtnord]

I think this would be clearer if exceptions where not used to control the flow - especially for the majority use case.

[jtnord]

https://github.com/hub4j/github-api/blob/a3a5a32e8d9447a46675d1439ba75e1e5a0ecf14/src/main/java/org/kohsuke/github/GitHubClient.java#L324-L327

[jtnord]

Looking at this again - I do not think this is even the correct fix and only fixes half the issue (if the other half is fixed then this is not needed at all).

Basically the image is not loaded so the browser is falling back to what it should do - the "alt text" (which is "GitHub Organisation")

if image loading is disabled you will see exactly the same issue against the public github.com (shown here for ci.jenkins.io)

The issue would seem to be that the alt text is too wide for the column (and the column is not resizing) to accommodate it.

[car-roll]

Looks like there hasn't been an incremental generated since the first commit. Apparently they are just spotless errors 😞