Building "#f92d61b1f4e193bd"  fails
When I run choosenim to build Nim at this commit it fails. Full output below.

```shell
  1 choosenim "#f92d61b1f4e193bd"
  2 Downloading Nim f92d61b1f4e193bd from GitHub
  3       Info: /home/person/.choosenim/downloads/f92d61b1f4e193bd.tar.gz already downloaded
  4  Extracting f92d61b1f4e193bd.tar.gz
  5    Building Nim #f92d61b1f4e193bd
  6    Warning: Building from latest C sources. They may not be compatible with the Nim version you have chosen to install.
  7       Info: /home/person/.choosenim/downloads/master.tar.gz already downloaded
  8  Extracting master.tar.gz
  9    Building C sources
 10    Building koch
 11  Exception: Execution failed with exit code 1
 12         ... Command: ./bin/nim c koch
 13         ... Output: Hint: used config file '/home/person/.choosenim/toolchains/nim-#f92d61b1f4e193bd/config/nim.cfg' [Conf]
 14         ... Hint: used config file 'koch.nim.cfg' [Conf]
 15         ... Hint: system [Processing]
 16         ... lib/system.nim(3990, 10) Error: type mismatch: got <string, nil>
 17         ... but expected one of:
 18         ... proc `==`[Enum: enum](x, y: Enum): bool
 19         ...   first type mismatch at position: 1
 20         ...   required type: Enum: enum
 21         ...   but expression 'x' is of type: string
 22         ... proc `==`(x, y: float32): bool
 23         ...   first type mismatch at position: 1
 24         ...   required type: float32
 25         ...   but expression 'x' is of type: string
 26         ... proc `==`(x, y: int16): bool
 27         ...   first type mismatch at position: 1
 28         ...   required type: int16
 29         ...   but expression 'x' is of type: string
 30         ... proc `==`[I, T](x, y: array[I, T]): bool
 31         ...   first type mismatch at position: 1
 32         ...   required type: array[I, T]
 33         ...   but expression 'x' is of type: string
 34         ... proc `==`(x, y: bool): bool
 35         ...   first type mismatch at position: 1
 36         ...   required type: bool
 37         ...   but expression 'x' is of type: string
 38         ... proc `==`[T: tuple |
 39         ...     object](x, y: T): bool
 40         ...   first type mismatch at position: 1
 41         ...   required type: T: tuple or object
 42         ...   but expression 'x' is of type: string
 43         ... proc `==`(x, y: char): bool
 44         ...   first type mismatch at position: 1
 45         ...   required type: char
 46         ...   but expression 'x' is of type: string
 47         ... proc `==`[T](x, y: ref T): bool
 48         ...   first type mismatch at position: 1
 49         ...   required type: ref T
 50         ...   but expression 'x' is of type: string
 51         ... proc `==`(x, y: string): bool
 52         ...   first type mismatch at position: 2
 53         ...   required type: string
 54         ...   but expression 'nil' is of type: nil
 55         ... proc `==`[T: proc](x, y: T): bool
 56         ...   first type mismatch at position: 1
 57         ...   required type: T: proc
 58         ...   but expression 'x' is of type: string
 59         ... proc `==`[T](x, y: ptr T): bool
 60         ...   first type mismatch at position: 1
 61         ...   required type: ptr T
 62         ...   but expression 'x' is of type: string
 63         ... proc `==`(x, y: int8): bool
 64         ...   first type mismatch at position: 1
 65         ...   required type: int8
 66         ...   but expression 'x' is of type: string
 67         ... proc `==`(x, y: int64): bool
 68         ...   first type mismatch at position: 1
 69         ...   required type: int64
 70         ...   but expression 'x' is of type: string
 71         ... proc `==`(x, y: pointer): bool
 72         ...   first type mismatch at position: 1
 73         ...   required type: pointer
 74         ...   but expression 'x' is of type: string
 75         ... proc `==`[T: SomeUnsignedInt](x, y: T): bool
 76         ...   first type mismatch at position: 1
 77         ...   required type: T: SomeUnsignedInt
 78         ...   but expression 'x' is of type: string
 79         ... proc `==`[T](x, y: set[T]): bool
 80         ...   first type mismatch at position: 1
 81         ...   required type: set[T]
 82         ...   but expression 'x' is of type: string
 83         ... proc `==`(x, y: float): bool
 84         ...   first type mismatch at position: 1
 85         ...   required type: float
 86         ...   but expression 'x' is of type: string
 87         ... proc `==`(x, y: int32): bool
 88         ...   first type mismatch at position: 1
 89         ...   required type: int32
 90         ...   but expression 'x' is of type: string
 91         ... proc `==`[T](x, y: seq[T]): bool
 92         ...   first type mismatch at position: 1
 93         ...   required type: seq[T]
 94         ...   but expression 'x' is of type: string
 95         ... proc `==`(x, y: int): bool
 96         ...   first type mismatch at position: 1
 97         ...   required type: int
 98         ...   but expression 'x' is of type: string
 99         ... expression: x == nil
100    Cleaning failed build
101        Tip: 7 messages have been suppressed, use --verbose to show them.
102      Error: Build failed
````