Explaining how to deal with cyclic dependency problems within Jenkins-builds.

doc/articles/troubleshooting.md

@@ -58,6 +58,11 @@ This is a list of common pitfalls on using Composer, and how to avoid them.
    Use: `before_script: COMPOSER_ROOT_VERSION=dev-master composer install` to export
    the variable for the call to composer.
 
+## Package not found in a Jenkins-build
+
+1. Check the ["Package not found"](#package-not-found) item above.
+2. Reason for failing is similar to the problem which can occur on travis-ci.org: The git-clone / checkout within Jenkins leaves the branch in a "detached HEAD"-state. As a result, composer is not able to identify the version of the current checked out branch and may not be able to resolve a cyclic dependency. To solve this problem, you can use the "Additional Behaviours" -> "Check out to specific local branch" in your Git-settings for your Jenkins-job, where your "local branch" shall be the same branch as you are checking out. Using this, the checkout will not be in detached state any more and cyclic dependency is recognized correctly.
+
 ## Need to override a package version
 
 Let say your project depends on package A which in turn depends on a specific