[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.

This makes the `_MESHROOM_COMPUTE_EXE` variable node-dependent whenever
we are not in release mode.

Author: cbentejac

meshroom/core/desc/node.py

@@ -20,7 +20,9 @@
     _MESHROOM_COMPUTE_EXE = _MESHROOM_COMPUTE
 else:
     _MESHROOM_COMPUTE = (Path(_MESHROOM_ROOT) / "bin" / "meshroom_compute").as_posix()
-    _MESHROOM_COMPUTE_EXE = f"python {_MESHROOM_COMPUTE}"
+    # _MESHROOM_COMPUTE_EXE will be set for each node individually, in case the Python executable for
+    # that node would differ from "python"
+    _MESHROOM_COMPUTE_EXE = ""
 
 
 class MrNodeType(enum.Enum):
@@ -261,7 +263,12 @@ 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"
+        if _MESHROOM_COMPUTE_EXE == "":
+            meshroomComputeCmd = f"{chunk.node.nodeDesc.pythonExecutable} {_MESHROOM_COMPUTE}"
+        else:
+            meshroomComputeCmd = f"{_MESHROOM_COMPUTE_EXE}"
+
+        meshroomComputeCmd += f" {chunk.node.graph.filepath} --node {chunk.node.name} --extern --inCurrentEnv"
 
         if len(chunk.node.getChunks()) > 1:
             meshroomComputeCmd += f" --iteration {chunk.range.iteration}"