I want to copy an artifact from a Matrix configuration (not the Matrix project itself) based on a promotion permalink.
Setup: The matrix project has one user defined axis with 2 values. AXIS=VALUE1 VALUE2. And a simple manual promotion named "My Promotion".
A different project wants the promoted artifact from AXIS=VALUE1.

Copy artifact from another project
Project name: JOBNAME/AXIS=VALUE1
Which build: Specified by Permalink
Permalink: My Promotion

Build and promote the matrix project.
Build the second project.
Console log gives me the "helpful" message:
ERROR: Unable to find a build for artifact copy from: JOBNAME/AXIS=VALUE1

From what I found out the problem is that JOBNAME/AXIS=VALUE (hudson.matrix.MatrixConfiguration) has no promotion permalinks (only the main project (hudson.matrix.MatrixProject) has them). And with that copyartifact gives up and says build not found.