# If we're not comparing against something and we have multiple
# parents then it's a merge commit so show what was merged.
- my $sha1 = $parent eq '-c' && @{[$self->parents]} > 1
+ my $sha1 = $parent && $parent eq '-c' && @{[$self->parents]} > 1
? sprintf("%s^1..%s^2", ($self->sha1) x 2)
: $self->sha1;