content of subfield not found

[Johann Rolschewski]

data:

### 02020nM2.01200024      h
001 47918-4
542aISSN 0724-8679
545a�aISSN 0724-8679 = C't

cli:

$ catmandu convert MAB2 --type Disk to YAML < data
---
_id: 47918-4
record:
- - LDR
  - ''
  - _
  - 02020nM2.01200024      h
- - '001'
  - ' '
  - _
  - 47918-4
- - '542'
  - a
  - _
  - ISSN 0724-8679
- - '545'
  - a
...

[Johann Rolschewski]

fixed in cb5ff41