BuffferedColumnResultProxy with compiled_cache corrupts result metadata

from sqlalchemy import create_engine, select, TypeDecorator, String, literal
from sqlalchemy.engine import default
from sqlalchemy.engine import result


class ExcCtx(default.DefaultExecutionContext):

    def get_result_proxy(self):
        return result.BufferedColumnResultProxy(self)

engine = create_engine("sqlite://")
engine.dialect.execution_ctx_cls = ExcCtx


class MyType(TypeDecorator):
    impl = String()

    def process_result_value(self, value, dialect):
        return "HI " + value

with engine.connect() as conn:
    stmt = select([literal("THERE", type_=MyType())])
    for i in range(2):
        r = conn.execute(stmt)
        assert r.scalar() == "HI THERE"

with engine.connect() as conn:
    cache = {}
    conn = conn.execution_options(compiled_cache=cache)

    stmt = select([literal("THERE", type_=MyType())])
    for i in range(2):
        r = conn.execute(stmt)
        assert r.scalar() == "HI THERE"
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