Get the pinned version of an InstallRequirement.

    An InstallRequirement is considered pinned if:

    - Is not editable
    - It has exactly one specifier
    - That specifier is "=="
    - The version does not contain a wildcard

    Examples:
        django==1.8   # pinned
        django>1.8    # NOT pinned
        django~=1.8   # NOT pinned
        django==1.*   # NOT pinned

    Raises `TypeError` if the input is not a valid InstallRequirement, or
    `ValueError` if the InstallRequirement is not pinned.

def get_pinned_version(ireq):
    """Get the pinned version of an InstallRequirement.

    An InstallRequirement is considered pinned if:

    - Is not editable
    - It has exactly one specifier
    - That specifier is "=="
    - The version does not contain a wildcard

    Examples:
        django==1.8   # pinned
        django>1.8    # NOT pinned
        django~=1.8   # NOT pinned
        django==1.*   # NOT pinned

    Raises `TypeError` if the input is not a valid InstallRequirement, or
    `ValueError` if the InstallRequirement is not pinned.
    """
    try:
        specifier = ireq.specifier
    except AttributeError:
        raise TypeError("Expected InstallRequirement, not {}".format(
            type(ireq).__name__,
        ))

    if ireq.editable:
        raise ValueError("InstallRequirement is editable")
    if not specifier:
        raise ValueError("InstallRequirement has no version specification")
    if len(specifier._specs) != 1:
        raise ValueError("InstallRequirement has multiple specifications")

    op, version = next(iter(specifier._specs))._spec
    if op not in ('==', '===') or version.endswith('.*'):
        raise ValueError("InstallRequirement not pinned (is {0!r})".format(
            op + version,
        ))

    return version