nixos-render-docs: print exception trees by __cause__

__context__ is always set to the prior exception, even when not using
the raise from form. __cause__ is only set during raise from. use
__cause__ so we can override a leaf exception (eg KeyError to something
more meaningful).

1 files changed, 2 insertions, 2 deletions

diff --git a/pkgs/tools/nix/nixos-render-docs/src/nixos_render_docs/__init__.py b/pkgs/tools/nix/nixos-render-docs/src/nixos_render_docs/__init__.py
index 67d7bce0047..56b68ba27a5 100644
--- a/pkgs/tools/nix/nixos-render-docs/src/nixos_render_docs/__init__.py
+++ b/pkgs/tools/nix/nixos-render-docs/src/nixos_render_docs/__init__.py
@@ -29,9 +29,9 @@ def pretty_print_exc(e: BaseException, *, _desc_text: str = "error") -> None:
             print(textwrap.indent(extra_info, "\t"), file=sys.stderr, end="")
     else:
         print(e)
-    if e.__context__ is not None:
+    if e.__cause__ is not None:
         print("", file=sys.stderr)
-        pretty_print_exc(e.__context__, _desc_text="caused by")
+        pretty_print_exc(e.__cause__, _desc_text="caused by")
 
 def main() -> None:
     parser = argparse.ArgumentParser(description='render nixos manual bits')