Warning on use of operator ===

[evnu]

Since 1.2.0, properties seem to result in a warning message use of operator === has no effect. Example module:

defmodule PropcheckMultipleExprWarningTest do
  use ExUnit.Case
  use PropCheck

  property "A Property" do
    forall x <- nat() do
      x >= 0
    end
  end
end

$ mix test
...
warning: use of operator === has no effect
  test/propcheck_multiple_expr_warning_test.exs:6

warning: use of operator === has no effect
  test/propcheck_multiple_expr_warning_test.exs:10

I believe this is caused by #118. The warning is present in this Travis job (
93426c6, commit from that PR), but it is not present in this Travis job (d1dc288, a commit shortly before that PR was merged).

[evnu]

I think this has been fixed "accidentally" with #126, specifically with c60f7a8. With the current master, I cannot reproduce the warnings from the example above anymore.

Interestingly, the warning was caused by this line in propcheck.ex (introduced in 9c1e9c3, part of #118):

env_verbose? = System.get_env("PROPCHECK_VERBOSE") == "1"

If I set env_verbose? to true on 161da5c (the commit prior to c60f7a8), the warning is gone. I cannot explain this warning, but at least it is gone now.