Thanks for coming back to me on this.
We created a tiny Jenkins project that demonstrates what is the problem is (attached here).
To make it short: P4_CLIENT environment variable has not the right value on one of the build agents.
With the tiny multi-configuration project attached, we build on two agents, corresponding to labels "db7" and "db9" (presumably two platforms on which we wish to run tests).
The Build step:
The problem is easy to spot if you take a look at the console outputs. Here, project would fail on agent "db7" these are the relevant parts of the console output:
P4: found 775729 revision in P4: builds: 775729
[db7] $ /bin/sh /tmp/jenkins7931966404345516969.sh
As you can see, the client automatically created by theP4 plugin is jenkins-philippe2-msycmp517_nfs-p4plugin-test-platform-db7-1 whereas the value of variable P4_CLIENT is jenkins-philippe2-msycmp504_nfs-p4plugin-test-platform-db9-8.
After downgrading to 1.9.5, both names are identical, which is expected.