Fix 1255-possible-regression-appendenv-in-powershell-fails-if-env-variable-does-not-exist-already (#1285)

* Fix error with Get-ChildItem by silently continuing

Signed-off-by: Thorsten Kaufmann <[email protected]>

Author: instinct-vfx

src/rezplugins/shell/_utils/powershell_base.py

@@ -273,10 +273,11 @@ def appendenv(self, key, value):
 
         # Be careful about ambiguous case in pwsh on Linux where pathsep is :
         # so that the ${ENV:VAR} form has to be used to not collide.
+        # The nested Get-ChildItem call is set to SilentlyContinue to prevent
+        # an exception of the Environment Variable is not set already
         self._addline(
-            'Set-Item -Path "Env:{0}" -Value ((Get-ChildItem "Env:{0}").Value + "{1}{2}")'.format(
-                key, self.pathsep, value)
-        )
+            'Set-Item -Path "Env:{0}" -Value ((Get-ChildItem -ErrorAction SilentlyContinue "Env:{0}").Value + "{1}{2}")'
+            .format(key, os.path.pathsep, value))
 
     def unsetenv(self, key):
         self._addline(r"Remove-Item Env:\%s" % key)