Apollo Datasource adds content-type: header when Content-Type (case sensitive) header is set

[AaronMoat]

https://github.com/apollographql/datasource-rest/blame/9a8b6278d80bc677fa7608ac0c3f065d991a79af/src/RESTDataSource.ts#L486

If this.get or similar is called with headers: { 'Content-Type': 'x' }, two duplicate headers get set (content-type and Content-Type).

This can cause problems in the API resulting in problematic behaviour.

[glasser]

Looks like a PR was filed (by a colleague of yours?): #154.

[AaronMoat]

Not a colleague of mine, just seem to have run into the same problem at the same time :)

[JustinSomers]

@AaronMoat We were able to get #154 merged in:
bb0cff0