Fix bug #5087: Improve the error message on record with duplicated fields.
Fix bug #5087: Improve the error message on record with duplicated fields.

maximedenes/coq,gares/coq,JasonGross/coq,ppedrot/coq,ppedrot/coq,Matafou/coq,amintimany/coq,letouzey/coq-wip,JasonGross/coq,gares/coq,silene/coq,SkySkimmer/coq,letouzey/coq-wip,silene/coq,amintimany/coq,william-lawvere/coq,ejgallego/coq,letouzey/coq-wip,ejgallego/coq,coq/coq,Zimmi48/coq,maximedenes/coq,Ptival/coq,gares/coq,coq/coq,Matafou/coq,JasonGross/coq,william-lawvere/coq,Ptival/coq,maximedenes/coq,silene/coq,Zimmi48/coq,Lionel-Rieg/coq,ppedrot/coq,ppedrot/coq,Matafou/coq,ejgallego/coq,JasonGross/coq,Zimmi48/coq,Lionel-Rieg/coq,amintimany/coq,maximedenes/coq,letouzey/coq-wip,letouzey/coq-wip,gares/coq,maximedenes/coq,SkySkimmer/coq,gares/coq,coq/coq,Zimmi48/coq,ppedrot/coq,SkySkimmer/coq,Ptival/coq,Lionel-Rieg/coq,william-lawvere/coq,SkySkimmer/coq,ejgallego/coq,coq/coq