fix unkown command elxir with rtx and fish (#1019) #1090

Job	Run time
static analysis (Elixir 1.15.x \| Erlang/OTP 25.x)	25s
mix test windows (Elixir 1.13.x \| Erlang/OTP 22.x)	8m 13s
mix test (Elixir 1.13.x \| Erlang/OTP 22.x)	4m 23s
mix test windows (Elixir 1.13.x \| Erlang/OTP 23.x)	10m 20s
mix test (Elixir 1.13.x \| Erlang/OTP 23.x)	7m 43s
mix test windows (Elixir 1.13.x \| Erlang/OTP 24.x)	8m 13s
mix test (Elixir 1.13.x \| Erlang/OTP 24.x)	5m 6s
mix test windows (Elixir 1.13.x \| Erlang/OTP 25.x)	5m 34s
mix test (Elixir 1.13.x \| Erlang/OTP 25.x)	3m 0s
mix test windows (Elixir 1.14.x \| Erlang/OTP 23.x)	10m 25s
mix test (Elixir 1.14.x \| Erlang/OTP 23.x)	6m 11s
mix test windows (Elixir 1.14.x \| Erlang/OTP 24.x)	7m 58s
mix test (Elixir 1.14.x \| Erlang/OTP 24.x)	3m 35s
mix test windows (Elixir 1.14.x \| Erlang/OTP 25.x)	6m 43s
mix test (Elixir 1.14.x \| Erlang/OTP 25.x)	2m 57s
mix test windows (Elixir 1.15.x \| Erlang/OTP 24.x)	4m 42s
mix test (Elixir 1.15.x \| Erlang/OTP 24.x)	3m 22s
mix test windows (Elixir 1.15.x \| Erlang/OTP 25.x)	5m 38s
mix test (Elixir 1.15.x \| Erlang/OTP 25.x)	3m 7s
	1h 47m 35s

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