Cleanup tmp dir *before* creating the prefix

Author: martinRenou

jupyterlite_xeus_python/env_build_addon.py

@@ -81,7 +81,9 @@ def __init__(self, *args, **kwargs):
         self.root_prefix = "/tmp/xeus-python-kernel"
         self.env_name = "xeus-python-kernel"
 
-        self.prefix_path.mkdir(parents=True, exist_ok=True)
+        # Cleanup tmp dir in case it's not empty
+        shutil.rmtree(self.root_prefix, ignore_errors=True)
+        Path(self.root_prefix).mkdir(parents=True, exist_ok=True)
 
         self.orig_config = os.environ.get("CONDARC")
 
@@ -91,9 +93,6 @@ def pre_build(self, manager):
         if not self.packages:
             return []
 
-        # Cleanup tmp dir
-        shutil.rmtree(self.root_prefix, ignore_errors=True)
-
         # Create emscripten env with the given packages
         self.create_env()
 
@@ -159,6 +158,8 @@ def create_env(self):
             channels.extend(["-c", channel])
 
         if MAMBA_AVAILABLE:
+            # Mamba needs the directory to exist already
+            self.prefix_path.mkdir(parents=True, exist_ok=True)
             return self._create_env_with_config("mamba", channels)
 
         if MICROMAMBA_AVAILABLE: