My R session crashes when execute group_indices() with single argument like this:

group_indices(mtcars)

I couldn't investigate deeper, but it seemed to crash around here:

https://github.com/hadley/dplyr/blob/11dfbcacb68937312a02feb3345e000fcdb3c54e/R/RcppExports.R#L185

My session info is below:

> sessionInfo()
R version 3.1.2 (2014-10-31)
Platform: x86_64-pc-linux-gnu (64-bit)
locale:
 [1] LC_CTYPE=en_US.UTF-8 LC_NUMERIC=C         LC_TIME=C            LC_COLLATE=C
 [5] LC_MONETARY=C        LC_MESSAGES=C        LC_PAPER=C           LC_NAME=C
 [9] LC_ADDRESS=C         LC_TELEPHONE=C       LC_MEASUREMENT=C     LC_IDENTIFICATION=C
attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base
other attached packages:
[1] dplyr_0.4.0           ggplot2_1.0.0         RCurl_1.95-4.5        bitops_1.0-6
[5] jsonlite_0.9.14       httr_0.6.0            metricsgraphics_0.0.1
loaded via a namespace (and not attached):
 [1] DBI_0.3.1        MASS_7.3-35      Rcpp_0.11.3      assertthat_0.1   colorspace_1.2-4 digest_0.6.6
 [7] grid_3.1.2       gtable_0.1.2     magrittr_1.5     munsell_0.4.2    parallel_3.1.2   plyr_1.8.1
[13] proto_0.3-10     reshape2_1.4.1   scales_0.2.4     stringr_0.6.2    tools_3.1.2