Inconsistent encoding when running bazel --batch run //foo -- "$arg" on OS X

[damienmg]

From @aehlig's words:

"Open-sourcing //src/test/shell/integration:run_test showed that the encoding of arguments
for tests is inconsistent in batch mode (works in non batch mode, though).

bazel run //foo -- "$arg" and bazel --batch run //foo -- "$arg" use a different encoding.

internal ref: b/31448480

[jmmv]

Seems like a dup of #1775, but if it isn't, I don't have enough information to reproduce.