print squashed detected diff

Do not print the changes commit per commits for the commits within the
range, but directly print the whole diff of the range start to the range
end.

This behavior is possible by changing the `git log` command usage to
`git diff` instead.

git/src/commits_range.rs

@@ -9,12 +9,12 @@ pub struct CommitsRange {
 }
 
 impl CommitsRange {
-    pub fn to_str(&self) -> String {
-        return format!(
-            "{}..{}",
-            &self.from,
-            &self.to,
-        );
+    pub fn from(&self) -> &String {
+        return &self.from;
+    }
+
+    pub fn to(&self) -> &String {
+        return &self.to;
     }
 }
 

git/src/path_inspector.rs

@@ -14,9 +14,10 @@ pub fn has_changes_in_paths(
 ) -> bool {
     let mut cmd = Command::new("git");
     cmd
-        .arg("log")
-        .arg(commits_range.to_str())
+        .arg("diff")
         .arg("--stat")
+        .arg(commits_range.from())
+        .arg(commits_range.to())
         .args(paths)
         .current_dir(&working_directory)
     ;
@@ -28,9 +29,14 @@ pub fn has_changes_in_paths(
         .expect("Failed to run git log command.")
     ;
 
-    assert_or_panic(&result, &String::from("git log"));
+    assert_or_panic(&result, &String::from("git diff"));
 
-    info!("{}", String::from_utf8(result.stdout.to_vec()).unwrap());
+    info!(
+        "Detected diff from {} to {} :\n{}",
+        commits_range.from(),
+        commits_range.to(),
+        String::from_utf8(result.stdout.to_vec()).unwrap()
+    );
 
     return !result.stdout.is_empty();
 }