qsys-script: no output on stdout when called from TCL script

I realize I'm necroing a fairly old thread but it's the closest thing I've found to a non-solution to a similar problem and I'm hoping that there might be an answer here. I've got a couple of python programs that I want to run pre and post building. The pre and post processor runs on TCL so I created a couple TCL scripts to run the python programs. I would like the output of the programs to be put into the output transcript but adding "2>&1" does not seem to do the trick. Here's my TCL invocation for one of them:

# Runs the Python update_build_time.py script to update the
# system build package.
proc call_python {} {
	set output [exec python ../bin/update_build_time.py -o ../src/system_build_info_pkg.vhd 2>&1]
	puts $output
}
post_message "Executing run_update_build_time.tcl script..."
post_message "=================================================================="
post_message "Running system build update Python program"
call_python
post_message "=================================================================="

The output in Quartus while running is only the post_message text:

Info: Executing run_update_build_time.tcl script...
Info: ==================================================================
Info: Running system build update Python program
Info: ==================================================================
Info (23030): Evaluation of Tcl script ../bin/run_update_build_time.tcl was successful
Info: Quartus Prime Shell was successful. 0 errors, 0 warnings

Any ideas on how I might be able to get the output to display?