-dboost_disable_asserts (all caps) in Makevars not working?

I was trying to update my package eggCounts, but when I tried to do R CMD check --as-cran there was this warning:

>  checking compiled code ... WARNING
>     File ‘eggCounts/libs/eggCounts.so’:
>         Found ‘abort’, possibly from ‘abort’ (C)
>         Object: ‘Modules.o’

I did a search and it found this:

> grep -rnw '/home/b/crwang/PhD/Git/eggCount/eggCounts_dev/' -e 'assert'
> Binary file /home/b/crwang/PhD/Git/eggCount/eggCounts_dev/src/Modules.o matches
> Binary file /home/b/crwang/PhD/Git/eggCount/eggCounts_dev/src/eggCounts.so matches

I did not modify my Makevars or any of my stan models, the only difference I see is that the models.hpp code is now generated with Stan version 2.17.0 instead of 2.16.0 in the previous version of my package. Here is my session info:

R version 3.5.0 (2018-04-23)
Platform: x86_64-pc-linux-gnu (64-bit)
Running under: Ubuntu 16.04.5 LTS

Matrix products: default
BLAS: /usr/lib/atlas-base/libf77blas.so.3.0
LAPACK: /usr/lib/atlas-base/atlas/liblapack.so.3.0

 [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C               LC_TIME=en_US.UTF-8        LC_COLLATE=C               LC_MONETARY=en_US.UTF-8   
 [6] LC_MESSAGES=en_US.UTF-8    LC_PAPER=de_CH.UTF-8       LC_NAME=C                  LC_ADDRESS=C               LC_TELEPHONE=C            

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

other attached packages:
[1] BH_1.66.0-1        eggCounts_2.1      rstan_2.17.3       StanHeaders_2.17.2 ggplot2_3.0.0      Rcpp_0.12.18