IEV data anomaly (20201217): SOURCE contains document titles

```
[RAW] ISO/IEC Guide 99:2007, International vocabulary of metrology – Basic and general concepts and associated terms (VIM), 4.5, modified – The definition, and the term in English, have been replaced to adapt to usage in control technology.
{:source_ref=>"JCGM VIM",
:clause=>"4.5",
:relation_type=>
{:type=>:modified,
:modification=>
"The definition, and the term in English, have been replaced to adapt to usage in control technology."}}

Processing term 351-57-01 (eng)... extract_source_clause 'ISO/IEC Guide 51:1999, Safety aspects – Guidelines for their inclusion in standards, 3.5'
[RAW] ISO/IEC Guide 51:1999, Safety aspects – Guidelines for their inclusion in standards, 3.5
{:source_ref=>"ISO/IEC Guide 51:1999",
:clause=>"3.5",
:relation_type=>{:type=>:identical}}
```

I don't think we're supposed to have document titles inside the SOURCE field.