GitPython 3.1.50 Authentication Bypass via Joined Short Options

GitPython 3.1.50 fails to recognize joined short-option forms such as -u<value> (the short form of --upload-pack=<value>) when enforcing its default unsafe-option gate. When an application passes attacker-influenced clone options into Repo.clone_from(..., multi_options=..., allow_unsafe_options=False), an attacker can supply -u<helper> to bypass the gate that blocks --upload-pack/-u, causing Git to execute the specified helper command during clone. Fixed in 3.1.51.