Error on extract_corpora when terms are pulled from another project

[bhartmoore]

The project LEDU8 has a seemingly unusual setting for key terms, but one that is apparently allowed by Paratext. It causes extract_corpora.py to inappropriately search for a file that doesn't exist, and then error. It's likely not possible to extract terms in this case, but it would be good to check for this situation and give a warning rather than to fail looking for the inappropriately constructed filename OtherProject-metadata.txt. This is low-priority because (1) it's an infrequent occurrence and (2) the project text still extracts correctly; we just don't get the terms.

Settings file terms configuration:
<BiblicalTermsListSetting>OtherProject:LEDU8:Hughes(Id)BiblicalTerms.xml</BiblicalTermsListSetting>

Error thrown by extract_corpora.py:
OSError: unable to access bucket: 'silnlp' key: 'MT/terms/OtherProject-metadata.txt' version: None error: An error occurred (NoSuchKey) when calling the GetObject operation: The specified key does not exist.