"git: fatal: unknown value for config 'protocol.version': 2" when switching channels

[oSoMoN]

$ flutter channel dev
Switching to flutter channel 'dev'...
git: fatal: unknown value for config 'protocol.version': 2
Switching channels failed with error code 128.

This was caused by the following section in my local ~/.gitconfig:

[protocol]
    version = 2

I worked around the problem by commenting it out and re-running the flutter channel command.

It looks like the version of git embedded in the flutter snap is too old to understand the git V2 protocol.