Uploading with the same mtime and filename causes "internal server errors"

When uploading a file with the same mtime and name but different contents multiple times, I get "500 Internal Server Error" for all uploads after the 2nd upload.

Take e.g. the these three uploads. Each uploading to the same filename using the same mtime in the the `Upload-Metadata`, but each time a different content:

```
curl 'https://localhost:9200/remote.php/dav/spaces/fa7e8b99-933b-4b0d-bb68-d6fb96ef6a82$34fbbd0c-16ef-4ac4-956c-1c5df6645286' -H 'Content-Type: application/offset+octet-stream' -H 'Tus-Resumable: 1.0.0' -H 'Upload-Length: 4' -H 'Upload-Metadata: mtime MTczMDE2MDAwMA==,filename L3Rlc3Qx' -d'test' -uadmin:admin -vk
```

```
curl 'https://localhost:9200/remote.php/dav/spaces/fa7e8b99-933b-4b0d-bb68-d6fb96ef6a82$34fbbd0c-16ef-4ac4-956c-1c5df6645286' -H 'Content-Type: application/offset+octet-stream' -H 'Tus-Resumable: 1.0.0' -H 'Upload-Length: 4' -H 'Upload-Metadata: mtime MTczMDE2MDAwMA==,filename L3Rlc3Qx' -d'tast' -uadmin:admin -vk
```

```
curl 'https://localhost:9200/remote.php/dav/spaces/fa7e8b99-933b-4b0d-bb68-d6fb96ef6a82$34fbbd0c-16ef-4ac4-956c-1c5df6645286' -H 'Content-Type: application/offset+octet-stream' -H 'Tus-Resumable: 1.0.0' -H 'Upload-Length: 4' -H 'Upload-Metadata: mtime MTczMDE2MDAwMA==,filename L3Rlc3Qx' -d'tost' -uadmin:admin -vk
```

The first two requests work fine (the 2nd one creates a new revision of the file). The 3rd one however causes a 500
reply:

```
* upload completely sent off: 4 bytes
* TLSv1.3 (IN), TLS handshake, Newsession Ticket (4):
< HTTP/1.1 500 Internal Server Error
< Access-Control-Allow-Headers: Tus-Resumable, Upload-Length, Upload-Metadata, If-Match
< Access-Control-Expose-Headers: Tus-Resumable, Upload-Offset, Location
< Content-Length: 0
< Content-Security-Policy: child-src 'self'; connect-src 'self' blob: https://raw.githubusercontent.com/owncloud/awesome-ocis/; default-src 'none'; font-src 'self'; frame-ancestors 'self'; frame-src 'self' blob: https://embed.diagrams.net/; img-src 'self' data: blob: https://raw.githubusercontent.com/owncloud/awesome-ocis/; manifest-src 'self'; media-src 'self'; object-src 'self' blob:; script-src 'self' 'unsafe-inline'; style-src 'self' 'unsafe-inline'
< Date: Wed, 06 Nov 2024 15:23:23 GMT
< Location: https://localhost:9200/data/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJhdWQiOiJyZXZhIiwiZXhwIjoxNzMwOTkzMDAzLCJpYXQiOjE3MzA5MDY2MDMsInRhcmdldCI6Imh0dHA6Ly9sb2NhbGhvc3Q6OTE1OC9kYXRhL3R1cy8wNWQyYTkzZC1mYjI0LTQyMDAtOTVlOC0zY2ZjOGQ3NzQwYWUifQ.LAQTnICsTdNOWYzk5Qp6ms2mkGckBmtxu5IqK48S4XA
< Referrer-Policy: strict-origin-when-cross-origin
< Strict-Transport-Security: max-age=315360000; preload
< Tus-Extension: creation,creation-with-upload,checksum,expiration
< Tus-Resumable: 1.0.0
< Vary: Origin
< X-Content-Type-Options: nosniff
< X-Frame-Options: SAMEORIGIN
< X-Permitted-Cross-Domain-Policies: none
< X-Request-Id: 58004e224a1a/p6IS9fNsSR-000089
< X-Robots-Tag: none
< X-Xss-Protection: 1; mode=block
<
```

_Originally posted by @rhafer in https://github.com/owncloud/ocis/issues/9498#issuecomment-2460082092_