subcommand: Parse and propagate [env] vars at the earliest possible moment (#18)

Strangely enough I added this call at a random place in
`Subcommand::new()`, instead of considering that it was both:
1. Breaking the logic for deducing `target_dir` in two separated blocks;
2. Preventing the first block - which reads environment variables! -
   from seeing what was configured in `.cargo/config.toml` through
   `[env]`.

Fix this by moving the call straight after identifying the root
directory for the selected package.

Author: MarijnS95

src/subcommand.rs

@@ -43,6 +43,13 @@ impl Subcommand {
         )?;
         let root_dir = manifest_path.parent().unwrap();
 
+        // TODO: Find, parse, and merge _all_ config files following the hierarchical structure:
+        // https://doc.rust-lang.org/cargo/reference/config.html#hierarchical-structure
+        let config = LocalizedConfig::find_cargo_config_for_workspace(&root_dir)?;
+        if let Some(config) = &config {
+            config.set_env_vars().unwrap();
+        }
+
         let target_dir = args
             .target_dir
             .clone()
@@ -59,13 +66,6 @@ impl Subcommand {
                 }
             });
 
-        // TODO: Find, parse, and merge _all_ config files following the hierarchical structure:
-        // https://doc.rust-lang.org/cargo/reference/config.html#hierarchical-structure
-        let config = LocalizedConfig::find_cargo_config_for_workspace(&root_dir)?;
-        if let Some(config) = &config {
-            config.set_env_vars().unwrap();
-        }
-
         let target_dir = target_dir.unwrap_or_else(|| {
             utils::find_workspace(&manifest_path, &package)
                 .unwrap()