When a exclude-norecurse pattern ends with a trailing slash, Borg still recurses one level below the excluded path

## Have you checked borgbackup docs, FAQ, and open Github issues?

Yes. #3209 might be related.

## Is this a BUG / ISSUE report or a QUESTION?

ISSUE

## System information. For client/server mode post info for both machines.

#### Your borg version (borg -V).

1.2.2

#### Operating system (distribution) and version.

Arch Linux

#### Hardware / network configuration, and filesystems used.

n.a.

#### How much data is handled by borg?

n.a.

#### Full borg commandline that lead to the problem (leave away excludes and passwords)

see below

## Describe the problem you're observing.

When a exclude-norecurse pattern ends with a trailing slash, Borg still recurses one level below the excluded path. The exclude still works correct, but Borg should skip recursion.

~~~sh
# normal exclude works as expected
(venv) c0d3@z3r0:[~]# rm -rf repo; borg init -e none repo; venv/bin/borg -p create --pattern '- re:^test/' --list repo:: /test
x /test/Downloadx 0 N test
x /test/Downloadx/owh
x /test/blub
d /test

# without trailing slash: works as expected
(venv) c0d3@z3r0:[~]# rm -rf repo; borg init -e none repo; venv/bin/borg -p create --pattern '! re:^test' --list repo::test /test
x /test

# trailing slash, regex: Borg recurses (exclude still working correct, though)
(venv) c0d3@z3r0:[~]# rm -rf repo; borg init -e none repo; venv/bin/borg -p create --pattern '! re:^test/' --list repo::test /test
x /test/Downloadx 0 N test
x /test/blub
d /test

# same for sh:, just for comparison
(venv) c0d3@z3r0:[~]# rm -rf repo; borg init -e none repo; venv/bin/borg -p create --pattern '! sh:test' --list repo::test /test
x /test
(venv) c0d3@z3r0:[~]# rm -rf repo; borg init -e none repo; venv/bin/borg -p create --pattern '! sh:test/' --list repo::test /test
x /test/Downloadx 0 N test
x /test/blub
d /test
~~~