Randomly reproducible plugin loading issue

Three tests regularly but randomly fail in the runs:

The following tests FAILED:
	951 - PDI_example_trace_C (Failed)
	952 - PDI_example_trace_F (Failed)
	953 - PDI_example_trace_P (Failed)

With the following error:

  * unable to load `/tmp/pdi_plugins/libpdi_trace_plugin.so' /tmp/pdi_plugins/libpdi_trace_plugin.so: undefined symbol: _ZN3fmt2v612format_errorD1Ev, 
  * unable to load `/tmp/pdi_plugins/libpdi_trace_plugin.so' /tmp/pdi_plugins/libpdi_trace_plugin.so: undefined symbol: _ZN3fmt2v612format_errorD1Ev, 

This is a kind of problem we also see regularly elsewhere.