Identify revisions of dataset among commits of the JSON repo
- As a fetchers system
 - I want each commit of the JSON repository to correspond to a commit of the source repository
 - In order to allow the API and the UI to navigate through previous revisions of the data.
 
Acceptance criteria
- 
Each commit of the JSON repository MUST have a corresponding commit in the source repository.  - 
Each commit message of the JSON repository MUST reference the commit-ID of the corresponding commit in the source repository.  
Resources
- 
Vocabulary: a commit is a change in the repository; a revision is a change in the data from the point of view of the provider
 - 
A rewrite of the history may be done by a generic script instead of an option of each converter script.
 - 
It may be necessary in 2 identified cases:
- the history of the source repository was rewritten
 - the converter script evolved itself, creating commits in the JSON repository not corresponding to a revision of the data
 
 - 
Git tags may be used to identify revisions, using the same tag in the source and the JSON repositories.
 
Edited  by Christophe Benz