compilation issue with 0.17.0

# main.nim
import sequtils, math


iterator efibs: int {. closure .} =
  var prev = 1
  var cur  = 2
  yield 1
  yield 2
  while true:
    let sum = prev + cur
    prev = cur
    cur = sum
    yield sum

proc until( iter:   iterator: int,
            stopAt: int
           ): iterator: int {. closure .}  =
  return iterator: int =
    for i in iter():
      if i <= stopAt: yield i
      else: break


proc isEven(i:int):bool = (i mod 2) == 0

echo efibs.until(4_000_000)()
          .toSeq()
          .filter(isEven)
          .sum()

#[ command line output

jesse@yubintoo:~/src/blockout$ nim c main.nim
Hint: used config file '/home/jesse/nim/config/nim.cfg' [Conf]
Hint: system [Processing]
Hint: main [Processing]
Hint: sequtils [Processing]
Hint: math [Processing]
CC: main
Error: execution of an external compiler program 'gcc -c  -w  -I/home/jesse/nim/lib -o /home/jesse/src/blockout/nimcache/main.o /home/jesse/src/blockout/nimcache/main.c' failed with exit code: 1

/home/jesse/src/blockout/nimcache/main.c: In function ‘NimMainModule’:
/home/jesse/src/blockout/nimcache/main.c:582:44: error: redeclaration of ‘efibs’ with no linkage
    Env_maindotnim__exfSYnGAibIzlFbeF0CX8w* efibs;
                                            ^
/home/jesse/src/blockout/nimcache/main.c:579:44: note: previous declaration of ‘efibs’ was here
    Env_maindotnim__exfSYnGAibIzlFbeF0CX8w* efibs;
                                            ^
jesse@yubintoo:~/src/blockout$ nim --version
Nim Compiler Version 0.17.0 (2017-05-17) [Linux: amd64]
Copyright (c) 2006-2017 by Andreas Rumpf

git hash: d3f0f87e81e262ee25fd528aae5b6db0bdf78d5e
active boot switches: -d:release

]#