tests: better test

thanks to @mikael-s

algo/tests/should-get-tests/gzip-out.should

-!NO_LAUNCHER:
-rm -f out/out-*.vidjil
-
 !LAUNCH: $VIDJIL_DIR/$EXEC -g $VIDJIL_DIR/germline/homo-sapiens.g:IGH -b out-a $VIDJIL_DATA/clones_simul.fa
 
 $ Output
@@ -11,8 +8,9 @@ $ Output
 $ Output
 1: out-b.vidjil.gz
 
+!NO_LAUNCHER:
 !NO_EXTRA:
-gunzip out/out-b.vidjil.gz && diff -s -I '"....-..-..' -I "gz" -I "out-" out/out-a.vidjil out/out-b.vidjil ; echo "Diff: $?"
+gunzip -f out/out-b.vidjil.gz && diff -s -I '"....-..-..' -I "gz" -I "out-" out/out-a.vidjil out/out-b.vidjil ; echo "Diff: $?"
 
 $ Same output
 1:Diff: 0