When inside front matter you specified series with spaces,
then the opengraph template wouldn't detect other articles,
because in `.Site.Taxonomies.series` they are stored by
urlized key.
Example:
```yaml
series:
- My Series
```
```gohtml
{{/* in a template */}}
{{- $series := index .Site.Taxonomies.series$name }}
{{/* was resolved to */}}
{{- $series := index {'my-series': ...} "MySeries" }}
```
(cherry picked from commit d2d493ab5d6a054001a8448ea0de2949dac4b30e)
d6b2282582