fix: display color when NO_COLOR is an empty string

CHANGELOG.md

@@ -8,6 +8,8 @@
 
 ## Bugfixes
 
+- Fix `NO_COLOR` support, see #1421 (@acuteenvy)
+
 ## Changes
 
 - The default number of threads is now constrained to be at most 16. This should improve startup time on

src/main.rs

@@ -218,11 +218,13 @@ fn construct_config(mut opts: Opts, pattern_regexps: &[String]) -> Result<Config
     let ansi_colors_support = true;
 
     let interactive_terminal = std::io::stdout().is_terminal();
+
     let colored_output = match opts.color {
         ColorWhen::Always => true,
         ColorWhen::Never => false,
         ColorWhen::Auto => {
-            ansi_colors_support && env::var_os("NO_COLOR").is_none() && interactive_terminal
+            let no_color = env::var_os("NO_COLOR").is_some_and(|x| !x.is_empty());
+            ansi_colors_support && !no_color && interactive_terminal
         }
     };