azure-cli: Passing /dev/fd/0 to az storage blob upload no longer works

Description

With the azure CLI 2.0.12 and below, it was possible to upload a stream from STDIN to blob storage by an invocation like the following -

az storage blob upload -f /dev/fd/0 --max-connections 1 ....

Obviously this only worked on platforms that have /dev/fd, but otherwise this worked nicely to upload unknown-length streams we didn’t want to buffer to disk.

This appears to have been broken since https://github.com/Azure/azure-cli/commit/7d51854504343b298f27d401e7bbf3bef8ffa039 - I suspect it’s something to do with the MIME type detection. It now only uploads zero-byte file but otherwise exits successfully. Eyeballing the code suggests that passing --content-type should help, but this appeared to have no effect

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Environment summary

Install Method: How did you install the CLI? (e.g. pip, interactive script, apt-get, Docker, MSI, nightly)
Answer here: pip install azure-cli

CLI Version: What version of the CLI and modules are installed? (Use az --version)
Answer here:

azure-cli (2.0.15)

acr (2.0.11)
acs (2.0.14)
appservice (0.1.14)
batch (3.1.2)
billing (0.1.4)
cdn (0.0.7)
cloud (2.0.7)
cognitiveservices (0.1.7)
command-modules-nspkg (2.0.1)
component (2.0.7)
configure (2.0.10)
consumption (0.1.4)
container (0.1.9)
core (2.0.14)
cosmosdb (0.1.12)
dla (0.0.11)
dls (0.0.13)
eventgrid (0.1.3)
feedback (2.0.6)
find (0.2.6)
interactive (0.3.8)
iot (0.1.11)
keyvault (2.0.8)
lab (0.0.10)
monitor (0.0.9)
network (2.0.13)
nspkg (3.0.1)
profile (2.0.11)
rdbms (0.0.6)
redis (0.2.8)
resource (2.0.13)
role (2.0.11)
servicefabric (0.0.2)
sf (1.0.7)
sql (2.0.10)
storage (2.0.13)
vm (2.0.13)

OS Version: What OS and version are you using?
Answer here: CentOS 7

Shell Type: What shell are you using? (e.g. bash, cmd.exe, Bash on Windows)
Answer here: Bash