Compilation of ssete9 failed (on coq dev)

[Casteran]

The compilation of hydra-battles fails (on Zulip CI, coq dev) when trying to build gaia (Schutte), apparently because of a lexical error.

# File "./theories/schutte/ssete9.v", line 2207, characters 15-20:
  # Error: The reference Pzero was not found in the current environment.

I looked at ssete9.v code on coq-community. Line 2207 is the only place where =P and zero are sticked together, leading to consider Pzero as an undeclared identifier.

It could be related to a recent change in lexical analysis rules coq/coq#16322
Perhaps it would be enough to add a apace between =P and zero.