better debug info on addon install failure

scripts/addons/cam/tests/install_addon.py

@@ -2,12 +2,14 @@ import tempfile
 import sys
 import subprocess
 import pathlib
+import shutil
 
 INSTALL_CODE=f"""
 import bpy
 bpy.ops.preferences.addon_install(filepath='{sys.argv[1]}')
 bpy.ops.preferences.addon_enable(module='cam')
 bpy.ops.wm.save_userpref()
+import cam
 """
 
 NUM_RETRIES=10
@@ -15,14 +17,19 @@ NUM_RETRIES=10
 with tempfile.TemporaryDirectory() as td:
   file=pathlib.Path(td,"install.py")
   file.write_text(INSTALL_CODE)
-  command = f'blender -b -P "{str(file)}"'
+  
   # blender 4.0 installing addon crashes sometimes on mac github actions...
   for x in range(NUM_RETRIES):
     try:
-      subprocess.run(command, shell=True, check=True,stdout=subprocess.PIPE,stderr=subprocess.STDOUT,text=True)
+      subprocess.run([shutil.which('blender'),'-b','-P',str(file)], shell=False, check=True,stdout=subprocess.PIPE,stderr=subprocess.STDOUT,text=True)
+      print("installed addon okay")
       sys.exit(0)
     except subprocess.CalledProcessError as e:
       print("Install addon failed, retrying:",e)
+      print("Command output:")
+      print("------------------------------")
+      print(e.output)
+      print("------------------------------")
       for line in str(e.output):
         if line.startswith("Writing: "):
           crash_file=pathlib.Path(line[len("Writing: "):])