Blueprint exceptions are sometimes handled by other blueprint's exception handlers

[prryplatypus]

Describe the bug
Exceptions thrown from within one blueprint are sometimes handled by the exception handler of another, unrelated blueprint instead of by its own. I have not had time to check whether this happens all the time or only if specific conditions are met, but I have attached a code snippet with which the issue can be reproduced.

Code snippet

from sanic import Blueprint, HTTPResponse, Request, Sanic
from sanic.exceptions import SanicException
from sanic.response import text


class BaseException(SanicException):
    code: int
    description: str
    status_code: int
    headers: dict = {}


class ExceptionA(BaseException):
    error: str


class ExceptionB(BaseException):
    code = 0
    status_code = 400


class ExceptionBA(ExceptionB, ExceptionA):
    error = "foo"
    description = "Bar!"


app = Sanic("my_app")
bp1 = Blueprint("auth", url_prefix="/auth")
bp2 = Blueprint("token")


@bp1.route("/network", version=1)
async def error_bp1(_: Request):
    raise ExceptionBA()


@bp2.route("/token")
async def hello_bp2(_: Request):
    return text("P3rry7hePl4typu5")


bpg1 = Blueprint.group(bp1, version_prefix="/api/v")
bpg2 = Blueprint.group(bp2, url_prefix="/api/oauth2")


for bp in bpg1.blueprints:
    @bp.exception(BaseException)
    async def _(_, ex: BaseException) -> HTTPResponse:
        return text("BPG1_BaseException")

    @bp.exception(Exception)
    async def _(request: Request, ex: Exception) -> HTTPResponse:
        return text("BPG1_Exception")


for bp in bpg2.blueprints:
    @bp.exception(ExceptionA)
    async def _(_, ex: ExceptionA):
        return text("BPG2_ExceptionA")

    @bp.exception(Exception)
    async def _(request: Request, ex: Exception):
        return text("BPG2_Exception")


bpg_all = Blueprint.group(bpg1, bpg2)
app.blueprint(bpg_all)


if __name__ == "__main__":
    app.run(debug=True)

Expected behavior
When accessing /api/v1/auth/network, an exception is raised, which is captured by the bpg1 exception handler; rendering a final response which displays the string BPG1_BaseException.

Actual behavior
When accessing /api/v1/auth/network, an exception is raised, which is (somehow) captured by the bpg2 exception handler; rendering a final response which displays the string BPG2_ExceptionA.

Environment (please complete the following information):

• OS: Windows 10 Pro; 21H1; Compilation 19043.1165.
• Versions: Sanic 21.6.2; Routing 0.7.1

[komar007]

This seems to be related to #2202. With the fix for #2202, sanic produces the expected behavior.

[ahopkins]

See #2246