Truffleruby fails to encode float values with german locale

[larskanis]

Specs raise several similar issues. The float is encoded with traditional german decimal point , instead of ., so that the value is not recognized by PostgreSQL:

  7) PG::TypeMapByMriType should allow mixed type conversions
     Failure/Error: res = @conn.exec_params( "SELECT $1, $2, $3", [5, 1.23, :TestSymbol], 0, tm )
     
     PG::InvalidTextRepresentation:
       ERROR:  invalid input syntax for type double precision: "1,2300000000000000E+00"

The current sprintf() based implementation is not locale dependent per default on MRI. But it turned out, that it shows the same behavior, as soon as the application calls this for some reason:

setlocale(LC_NUMERIC, "de_DE.utf8");