Fix upstream merge conflict on ab538df0a976
Merging upstream commit ab538df0a976 gives a conflict.
A human being has to perform merge and resolution for the automatic merge process to resume.
Command for clean conflict reproduction:
hg pull
hg --config command.update.check=abort update 0f0cd756d9bc73139d62369e8c06e06685fb2926 && \
hg topic upstream-merge && \
hg merge ab538df0a97661ca41717decc9b94589810d9cae