Possible bug: anyone know what "WARNING: Caught an exception in the keymap:" means?

I’ve figured out the ERROR (but not exactly why I get the WARNING; I’m however no longer alarmed by it; but would still like to know what it means; it’s puzzling why it happens here, as opposed to the ERROR), it’s simply:

It must be because the REPL has to maintain the history file, but not when running directly (a better/clearer ERROR message, or that is WARNING, would be useful; or simply disabling it for the history file).

$ julia -e "versioninfo()"
Julia Version 0.5.0
Commit 3c9d753 (2016-09-19 18:14 UTC)
Platform Info:
  System: Linux (x86_64-linux-gnu)
  CPU: Intel(R) Xeon(R) CPU E3-1245 v5 @ 3.50GHz
  WORD_SIZE: 64
  BLAS: libopenblas (NO_LAPACKE DYNAMIC_ARCH NO_AFFINITY Haswell)
  LAPACK: liblapack.so.3
  LIBM: libopenlibm
  LLVM: libLLVM-3.7.1 (ORCJIT, broadwell)
qwerty@qwerty:~$ julia
               _
   _       _ _(_)_     |  A fresh approach to technical computing
  (_)     | (_) (_)    |  Documentation: http://docs.julialang.org
   _ _   _| |_  __ _   |  Type "?help" for help.
  | | | | | | |/ _` |  |
  | | |_| | | | (_| |  |  Version 0.5.0 (2016-09-19 18:14 UTC)
 _/ |\__'_|_|_|\__'_|  |  
|__/                   |  x86_64-linux-gnu

julia> versioninfo()
WARNING: Caught an exception in the keymap:
ERROR: SystemError: flush: No space left on device
Julia Version 0.5.0
Commit 3c9d753 (2016-09-19 18:14 UTC)
Platform Info:
  System: Linux (x86_64-linux-gnu)
  CPU: Intel(R) Xeon(R) CPU E3-1245 v5 @ 3.50GHz
  WORD_SIZE: 64
  BLAS: libopenblas (NO_LAPACKE DYNAMIC_ARCH NO_AFFINITY Haswell)
  LAPACK: liblapack.so.3
  LIBM: libopenlibm
  LLVM: libLLVM-3.7.1 (ORCJIT, broadwell)