Non reproducible build with elpi 2

[proux01]

With following file a.v

From elpi Require Import elpi.

Module M.
End M.

Elpi Command foo.
#[synterp] Elpi Accumulate "                                                                                                                                   
main _ :-                                                                                                                                                      
  coq.env.import-module { coq.locate-module ""M"" }.                                                                                                           
".
Elpi Accumulate "                                                                                                                                              
main _ :-                                                                                                                                                      
  coq.env.import-module { coq.locate-module ""M"" }.                                                                                                           
".
Elpi foo.

The command

coqc a.v && mv -f a.vo a.vo.bak && coqc a.v && diff a.vo a.vo.bak

answers

Binary files a.vo and a.vo.bak differ

(minimized with @CohenCyril )

FTR the pure Coq Module M. End M. Export M. is stable.

[proux01]

Only appeared with elpi >= 2.0, was not there with elpi 1.20

[proux01]

More precisely, my git bisect pointed to LPCIC/coq-elpi#719
First bad commit I was able to find being 87235d79fee8666391874d2a24560441f516c32b "Elpi File immediately scopes the program" (I wasn't able to compile older commits with a released version of elpi)

[gares]

Fixed by #303