`Blob.upload_from_filename` fails silently if the blob name starts with '/'

Using google-cloud-storage==1.2.0, attempting to upload files using Blob.upload_from_filename fails silently (i.e. no error is raised but the blob is not uploaded) if the blob name starts with a forward slash /. A basic example is given below.

import google.cloud.storage

client = google.cloud.storage.Client()
bucket = client.get_bucket('some-bucket')
blob = bucket("/some-blob")
blob.upload_from_filename("some-file")

[tillahoffmann]

I can no longer reproduce this issue using 1.3.0.

[tseaver]

I still cannot reproduce this issue:

$ python3.9 -m venv /tmp/repro-gcp-3675
$ /tmp/repro-gcp-3675/bin/pip install google-cloud-storage
...
Successfully installed cachetools-4.2.2 certifi-2021.5.30 cffi-1.14.5 chardet-4.0.0 google-api-core-1.29.0 google-auth-1.30.1 google-cloud-core-1.6.0 google-cloud-storage-1.38.0 google-crc32c-1.1.2 google-resumable-media-1.3.0 googleapis-common-protos-1.53.0 idna-2.10 packaging-20.9 protobuf-3.17.2 pyasn1-0.4.8 pyasn1-modules-0.2.8 pycparser-2.20 pyparsing-2.4.7 pytz-2021.1 requests-2.25.1 rsa-4.7.2 six-1.16.0 urllib3-1.26.5
$ cat > /tmp/my_file.csv
"Date","Action","Count"
"2021-06-07","Testing", 1
$ cat /tmp/repro-gcp-3675/repro_gcp_3675.py 
from google.cloud.storage import Client

BUCKET_NAME = "repro-gcp-3675"
BLOBNAME = "/my_file.csv"
FILENAME = f"/tmp{BLOBNAME}"

def main():
    client = Client()
    bucket = client.get_bucket(BUCKET_NAME)
    blob = bucket.blob(BLOBNAME)
    blob.upload_from_filename(FILENAME)

    assert blob.exists()

    assert BLOBNAME in [blob.name for blob in bucket.list_blobs()]


if __name__ == "__main__":
    main()
$ /tmp/repro-gcp-3675/bin/python /tmp/repro-gcp-3675/repro_gcp_3675.py
$

Note that the google-cloud-storage library is no longer maintained in this repository. If you can provide a reproducible case for this issue, please open a new issue in the new repository.