CLI flag --config license_template_path does not override TOML setting

[cmichi]

Describe the bug

The flag --config license_template_path="" (or --config=license_template_path="", doesn't matter) does not override the license_template_path from the .rustfmt.toml.

According to --help it should:

        --config [key1=val1,key2=val2...]                                      
                        Set options from command line. These settings take
                        priority over .rustfmt.toml  

To Reproduce

echo 'license_template_path = "FILE_HEADER"' > .rustfmt.toml
echo "// Some license header" > FILE_HEADER 
echo "fn main() {}" > foo.rs

rustfmt --config license_template_path="" foo.rs

For me this then results in the license check still being applied and this error:

error: license check failed
--> /home/michi/projects/rustfmt-bug/foo.rs:1
 |
 |

warning: rustfmt has failed to format. See previous 1 errors.

Expected behavior

The expected behavior is what I get when I don't set any license_template_path in the toml:

$ echo 'license_template_path = ""' > .rustfmt.toml 
$ rustfmt --check foo.rs
$ echo $?
0

Meta

• rustfmt version: rustfmt 1.4.22-nightly (97d0301 2020-10-04)
• From where did you install rustfmt? rustup
• How do you run rustfmt: rustfmt

[karyon]

Looks like this was fixed in #4488, but wasn't auto-closed.