Regions GC: calling obstackPtr/setObstackPtr can leak

[clj]

Function echo outputs the wrong string.

Example

# --gc:regions -d:useMalloc
var obstackPtr = obstackPtr()

while true:
  var a = "a" & "b"
  setObstackPtr(obstackPtr)

Current Output

Killed

Expected Output

Additional Information

When making an allocation before calling obstackPtr the program works as expected:

# --gc:regions -d:useMalloc
var x = "a" & "b"

var obstackPtr = obstackPtr()

while true:
  var a = "a" & "b"
  setObstackPtr(obstackPtr)

$ nim -v
Nim Compiler Version 1.0.2 [Linux: amd64]