The fetch-pack/upload-pack protocol relies on the underlying transport (local pipe or TCP socket) to have enough slack to allow one window worth of data in flight without blocking the writer. Traditionally we always relied on being able to have two windows of 32 "have"s in flight (roughly 3k bytes) to stream.
The recent "progressive-stride" change allows "fetch-pack" to send up to 1024 "have"s without reading any response from "upload-pack". The outgoing pipe of "upload-pack" can be clogged with many ACK and NAK that are unread, while "fetch-pack" is still stuffing its outgoing pipe with more "have"s, leading to a deadlock.
Revert the change unless we are in stateless rpc (aka smart-http) mode, as using a large window full of "have"s is still a good way to help reduce the number of back-and-forth, and there is no buffering issue there (it is strictly "ping-pong" without an overlap).