test-mean.sh fails on macOS

[yegor256]

I'm getting this:

steps/aggregation-functions/test-mean.sh:
👍🏻 Single metric (LCOM5) mean calculated correctly
👍🏻 Multiple metrics (LCOM5, NHD) aggregated correctly
👍🏻 Mixed metrics aggregated correctly (LCOM5)

Parse error: bad expression
    <stdin>:1

❌ Non-zero exit code (TARGET=/Volumes/sec/code/cam/test-zone/steps/aggregation-functions/test-mean.sh/target)
You can run this particular test in isolation: make test TEST=tests/steps/aggregation-functions/test-mean.sh
make: *** [Makefile:83: test] Error 1

[dzhovi]

@yegor256 apparently the problem was in encoding of the result, so i fixed it in #409

Yet it is very interesting question why issues #406 and #405 so unexpectedly appeared