Macro bug with keyword arguments

[yurivish]

julia> macro foo(x)
           quote
               $x
           end
       end
@foo (macro with 1 method)

julia> f(; kwarg) = kwarg
f (generic function with 1 method)

julia> @foo f(kwarg = x -> x)
ERROR: syntax: "Main.x" is not a valid function argument name

It seems like the keyword argument specification is the culprit here. The same macro works on a call without a keyword argument:

julia> g(arg) = arg
g (generic function with 1 method)

julia> @foo g(x -> x)
#5 (generic function with 1 method)

---

julia> versioninfo()
Julia Version 1.0.0
Commit 5d4eaca0c9 (2018-08-08 20:58 UTC)
Platform Info:
  OS: macOS (x86_64-apple-darwin14.5.0)
  CPU: Intel(R) Core(TM) i7-3615QM CPU @ 2.30GHz
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-6.0.0 (ORCJIT, ivybridge)
Environment:
  JULIA_EDITOR = subl