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### Environment
* Elixir version (elixir -v):
```
Erlang/OTP 20 [erts-9.2] [source] [64-bit] [smp:8:8] [ds:8:8:10] [async-threads:10] [hipe] [kernel-poll:false] [dtrace]
Elixir 1.6.0 (compiled with OTP 20)
```
* Phoenix version (mix deps): 1.3.0
* NodeJS version (node -v): v6.10.0
* NPM version (npm -v): 4.3.0
* Operating system: Mac OS X
### Expected behavior
Dialyzer should not emit any warnings on a clean project.
### Actual behavior
Here are the steps to reproduce the Dialyzer warnings:
1. `mix phx.new hello --no-html`
2. Edit `mix.exs` file to include `{:dialyxir, "~> 0.5.1", only: :dev, runtime: false}` in the list of deps and `dialyzer: [flags: [:unmatched_returns, :error_handling, :race_conditions, :underspecs]]` in the project config
3. `mix deps.get`
4. `mix dialyzer`
```
hello $ mix dialyzer
==> dialyxir
Compiling 5 files (.ex)
Generated dialyxir app
==> hello
Compiling 10 files (.ex)
Generated hello app
Checking PLT...
[:asn1, :compiler, :connection, :cowboy, :cowlib, :crypto, :db_connection,
:decimal, :ecto, :eex, :elixir, :gettext, :kernel, :logger, :mime, :phoenix,
:phoenix_ecto, :phoenix_pubsub, :plug, :poison, :poolboy, :postgrex,
:public_key, :ranch, :runtime_tools, :ssl, :stdlib]
Finding suitable PLTs
Looking up modules in dialyxir_erlang-20.2.2_elixir-1.6.0_deps-dev.plt
Looking up modules in dialyxir_erlang-20.2.2_elixir-1.6.0.plt
Finding applications for dialyxir_erlang-20.2.2_elixir-1.6.0.plt
Finding modules for dialyxir_erlang-20.2.2_elixir-1.6.0.plt
Checking 391 modules in dialyxir_erlang-20.2.2_elixir-1.6.0.plt
Finding applications for dialyxir_erlang-20.2.2_elixir-1.6.0_deps-dev.plt
Finding modules for dialyxir_erlang-20.2.2_elixir-1.6.0_deps-dev.plt
Copying dialyxir_erlang-20.2.2_elixir-1.6.0.plt to dialyxir_erlang-20.2.2_elixir-1.6.0_deps-dev.plt
Looking up modules in dialyxir_erlang-20.2.2_elixir-1.6.0_deps-dev.plt
Checking 391 modules in dialyxir_erlang-20.2.2_elixir-1.6.0_deps-dev.plt
Adding 666 modules to dialyxir_erlang-20.2.2_elixir-1.6.0_deps-dev.plt
Starting Dialyzer
dialyzer args: [
check_plt: false,
init_plt: '/Users/fertapric/Desktop/hello/_build/dev/dialyxir_erlang-20.2.2_elixir-1.6.0_deps-dev.plt',
files_rec: ['/Users/fertapric/Desktop/hello/_build/dev/lib/hello/ebin'],
warnings: [:unmatched_returns, :error_handling, :race_conditions, :underspecs,
:unknown]
]
done in 0m2.04s
lib/phoenix/router.ex:2: Function call/2 has no local return
done (warnings were emitted)
```
It seems to be related to the `--no-html` flag, because doing the same with`mix phx.new hello` does not emit any warning.
