Do not try to convert strings in internal paths for *form* blocks

[cekk]

This could generate some problems for example when adding a field with options, and one option have the same name as a content id..we don't want to convert it into an internal path.

[coveralls]

Pull Request Test Coverage Report for Build 8233450572

Details

• 2 of 2 (100.0%) changed or added relevant lines in 2 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 63.953%

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Totals
Change from base Build 8231419485:	0.0%
Covered Lines:	864
Relevant Lines:	1351

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💛 - Coveralls