[Rd] Pressing either Ctrl-\ of Ctrl-4 core dumps R

[Henrik Bengtsson]

When running R from the terminal on Linux (Ubuntu 16.04), it core
dumps whenever / wherever I press Ctrl-4 or Ctrl-\.  You get thrown
back to the terminal with "Quit (core dump)" being the only message.
Grepping the R source code, it doesn't look like that message is
generated by R itself.  Over on Twitter, it has been confirmed to also
happen on macOS.

$ R -d valgrind --vanilla --quiet
==979== Memcheck, a memory error detector
==979== Copyright (C) 2002-2015, and GNU GPL'd, by Julian Seward et al.
==979== Using Valgrind-3.11.0 and LibVEX; rerun with -h for copyright info
==979== Command: /usr/lib/R/bin/exec/R --vanilla --quiet
==979==
> 1+2
[1] 3

# At next prompt I press Ctrl-\. The same happens also when done in
the middle of an entry.

> ==979==
==979== Process terminating with default action of signal 3 (SIGQUIT)
==979==    at 0x576C9C3: __select_nocancel (syscall-template.S:84)
==979==    by 0x502EABE: R_SelectEx (in /usr/lib/R/lib/libR.so)
==979==    by 0x502EDDF: R_checkActivityEx (in /usr/lib/R/lib/libR.so)
==979==    by 0x502F32B: ??? (in /usr/lib/R/lib/libR.so)
==979==    by 0x4F6988B: Rf_ReplIteration (in /usr/lib/R/lib/libR.so)
==979==    by 0x4F69CF0: ??? (in /usr/lib/R/lib/libR.so)
==979==    by 0x4F69DA7: run_Rmainloop (in /usr/lib/R/lib/libR.so)
==979==    by 0x4007CA: main (in /usr/lib/R/bin/exec/R)
==979==
==979== HEAP SUMMARY:
==979==     in use at exit: 28,981,596 bytes in 13,313 blocks
==979==   total heap usage: 27,002 allocs, 13,689 frees, 49,025,684
bytes allocated
==979==
==979== LEAK SUMMARY:
==979==    definitely lost: 0 bytes in 0 blocks
==979==    indirectly lost: 0 bytes in 0 blocks
==979==      possibly lost: 0 bytes in 0 blocks
==979==    still reachable: 28,981,596 bytes in 13,313 blocks
==979==         suppressed: 0 bytes in 0 blocks
==979== Rerun with --leak-check=full to see details of leaked memory
==979==
==979== For counts of detected and suppressed errors, rerun with: -v
==979== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)
Quit (core dumped)

$ R --version
R version 3.3.2 (2016-10-31) -- "Sincere Pumpkin Patch"
Copyright (C) 2016 The R Foundation for Statistical Computing
Platform: x86_64-pc-linux-gnu (64-bit)

/Henrik