Prevent non-docs stages when a PR only modifies docs/

[mikepapadim]

This is an intermediate fix for #8673.
It modifies Jenkinsfile to prevent non-doc related stages from running when only modifying in docs/.
The idea is to save some CI cycles and speed up the process of augmenting docs.

@areusch @comaniac @tqchen

[Hzfengsy]

Thanks, @mikepapadim. I agree that it is important to save the CI time.

However, tutorials may be changed even though the codes in docs/ are not changed. For example, when we change the printer(files in src/ and include) may still change the document. These changes are not often happened but they do exist.

[areusch]

@mikepapadim this looks much closer to what we want but I think if I'm reading this right, I see:

• whenever a change only modifies docs/, we skip all build, unit test, integration test steps

as @Hzfengsy said, we shouldn't ever skip these nodes:

• Sanity Check (this should already be correct in the patch now)
• BUILD: GPU
• docs: GPU

i think we need to find a way to propagate these conditions down to the node level in each stage (e.g. skip each node not listed above when changeset "docs/**" doesn't match). i'm not entirely sure how to do this.

[mikepapadim]

@mikepapadim this looks much closer to what we want but I think if I'm reading this right, I see:

• whenever a change only modifies docs/, we skip all build, unit test, integration test steps

as @Hzfengsy said, we shouldn't ever skip these nodes:

• Sanity Check (this should already be correct in the patch now)
• BUILD: GPU
• docs: GPU

i think we need to find a way to propagate these conditions down to the node level in each stage (e.g. skip each node not listed above when changeset "docs/**" doesn't match). i'm not entirely sure how to do this.

Yes, right now the changeset condition is in the stage scope, I will have another look on how to make use of it in node scope.

[leandron]

There are a couple unrelated changes to this patch. Apart from that, I agree in principle with the proposed change.

[leandron]

This seems like an unrelated change.

[leandron]

This seems like an unrelated change.