disambiguation error (note style)

[icornelius]

(Transferred from pandoc-discuss.)

citeproc fails to disambiguate later citations in note styles when the given bibliographic items are not each cited at least twice.
My markdown file reads as follows:

---
csl: PATH/TO/styles/modern-humanities-research-association.csl
references:
- id: Turville-PetrePuttingItRight2002
  author:
    - family: Turville-Petre
      given: Thorlac
  citation-key: Turville-PetrePuttingItRight2002
  container-title: Yearbook of Langland Studies
  issued:
    - year: 2002
  page: 41-65
  title: >-
    Putting it right: the corrections of Huntington Library MS. HM 128 and BL
    Additional MS. 35287
  title-short: Putting it right
  type: article-journal
  volume: '16'

- id: Turville-PetreSirAdrianFortescue2000
  author:
    - family: Turville-Petre
      given: Thorlac
  citation-key: Turville-PetreSirAdrianFortescue2000
  container-title: Yearbook of Langland Studies
  issued:
    - year: 2000
  page: 29-48
  title: Sir Adrian Fortescue and his copy of *Piers Plowman*
  title-short: Sir Adrian Fortescue
  type: article-journal
  volume: '14'
---

Lorem ipsum [@Turville-PetreSirAdrianFortescue2000; @Turville-PetrePuttingItRight2002].
Dolor sit [@Turville-PetrePuttingItRight2002].
<!--
Amet [@Turville-PetreSirAdrianFortescue2000].
-->

# Bibliography

Run, e.g.,

$ pandoc test.md --citeproc -o test.html

Result:

Notice that the citation in note 2 is ambiguous.

Now uncomment the final citation in the markdown file and run pandoc again. Result:

If both items are cited at least twice, citeproc disambiguates properly.