$ spack python -c 'from spack.spec import Spec; s = Spec("libtree@git.master"); s.intersects("libtree@1.1.0")'

$ spack python -c 'from spack.spec import Spec; s = Spec("libtree@git.master"); s.intersects("libtree@1.1.0")'
Traceback (most recent call last):
  File "/usr/lib/python3.8/code.py", line 90, in runcode
    exec(code, self.locals)
  File "<input>", line 1, in <module>
  File "/home/culpo/github/spack/lib/spack/spack/spec.py", line 3553, in intersects
    if not self.versions.intersects(other.versions):
  File "/home/culpo/github/spack/lib/spack/spack/version.py", line 1059, in intersects
    return self.overlaps(other)
  File "/home/culpo/github/spack/lib/spack/spack/version.py", line 108, in coercing_method
    return method(a, b, *args, **kwargs)
  File "/home/culpo/github/spack/lib/spack/spack/version.py", line 1050, in overlaps
    if self[s].overlaps(other[o]):
  File "/home/culpo/github/spack/lib/spack/spack/version.py", line 488, in overlaps
    return self.intersects(other)
  File "/home/culpo/github/spack/lib/spack/spack/version.py", line 111, in coercing_method
    return getattr(ca, method.__name__)(cb, *args, **kwargs)
  File "/home/culpo/github/spack/lib/spack/spack/version.py", line 108, in coercing_method
    return method(a, b, *args, **kwargs)
  File "/home/culpo/github/spack/lib/spack/spack/version.py", line 619, in intersects
    n = min(len(v1), len(v2))
TypeError: object of type 'NoneType' has no len()