[core] desc.node: Use node's Python executable to call meshroom_compute

If `pythonExecutable` has not been explicitly set in the node's
description, then the default `python` will be used. Otherwise, the
one set in the description will be used.

`_MESHROOM_COMPUTE_EXE` is removed since it is now impossible to
determine it outside of the node.

Author: cbentejac

meshroom/core/desc/node.py

@@ -16,7 +16,6 @@
 
 _MESHROOM_ROOT = Path(meshroom.__file__).parent.parent.as_posix()
 _MESHROOM_COMPUTE = (Path(_MESHROOM_ROOT) / "bin" / "meshroom_compute").as_posix()
-_MESHROOM_COMPUTE_EXE = f"python {_MESHROOM_COMPUTE}"
 
 
 class MrNodeType(enum.Enum):
@@ -257,7 +256,8 @@ def getMrNodeType(self):
         return MrNodeType.NODE
 
     def processChunkInEnvironment(self, chunk):
-        meshroomComputeCmd = f"{_MESHROOM_COMPUTE_EXE} {chunk.node.graph.filepath} --node {chunk.node.name} --extern --inCurrentEnv"
+        meshroomComputeCmd = f"{chunk.node.nodeDesc.pythonExecutable} {_MESHROOM_COMPUTE}"
+        meshroomComputeCmd += f" {chunk.node.graph.filepath} --node {chunk.node.name} --extern --inCurrentEnv"
 
         if len(chunk.node.getChunks()) > 1:
             meshroomComputeCmd += f" --iteration {chunk.range.iteration}"