Put file-modified label in front of mode changes.

When using `--navigate` with files that get their mode modified, the
file-modified label was not being prefixed, so these changes were not
being marked as skip destinations.  This is particularly bad if a file
has line changes along with the mode change AND the user has an empty
hunk label (since that would make the entire file's changes get skipped
with an "n").

I added a test of a mode-change with a line-change, and a test for a
mode change where the old & new mode values are not one of the two
expected value-pairs.  I also used format_file() on the mode filenames
since the other format() calls were using it.

src/handlers/diff_header.rs

@@ -334,11 +334,23 @@ pub fn get_file_change_description_from_file_paths(
             ) if minus_file == plus_file => match (old_mode.as_str(), new_mode.as_str()) {
                 // 100755 for executable and 100644 for non-executable are the only file modes Git records.
                 // https://medium.com/@tahteche/how-git-treats-changes-in-file-permissions-f71874ca239d
-                ("100644", "100755") => format!("{}: mode +x", plus_file),
-                ("100755", "100644") => format!("{}: mode -x", plus_file),
+                ("100644", "100755") => format!(
+                    "{}{}: mode +x",
+                    format_label(&config.file_modified_label),
+                    format_file(plus_file)
+                ),
+                ("100755", "100644") => format!(
+                    "{}{}: mode -x",
+                    format_label(&config.file_modified_label),
+                    format_file(plus_file)
+                ),
                 _ => format!(
-                    "{}: {} {} {}",
-                    plus_file, old_mode, config.right_arrow, new_mode
+                    "{}{}: {} {} {}",
+                    format_label(&config.file_modified_label),
+                    format_file(plus_file),
+                    old_mode,
+                    config.right_arrow,
+                    new_mode
                 ),
             },
             (minus_file, plus_file, _, _) if minus_file == plus_file => format!(

src/tests/test_example_diffs.rs

@@ -8,6 +8,7 @@ mod tests {
     use crate::tests::ansi_test_utils::ansi_test_utils;
     use crate::tests::integration_test_utils;
     use crate::tests::test_utils;
+    use regex::Regex;
 
     #[test]
     fn test_added_file() {
@@ -1606,6 +1607,40 @@ src/align.rs:71: impl<'a> Alignment<'a> { │
         assert!(output.contains(r"src/delta.rs: mode -x"));
     }
 
+    #[test]
+    fn test_file_mode_change_unexpected_bits() {
+        let config =
+            integration_test_utils::make_config_from_args(&["--navigate", "--right-arrow=->"]);
+        let output =
+            integration_test_utils::run_delta(GIT_DIFF_FILE_MODE_CHANGE_UNEXPECTED_BITS, &config);
+        let output = strip_ansi_codes(&output);
+        assert!(output.contains(r"Δ src/delta.rs: 100700 -> 100644"));
+    }
+
+    #[test]
+    fn test_file_mode_change_with_diff() {
+        let config = integration_test_utils::make_config_from_args(&[
+            "--navigate",
+            "--keep-plus-minus-markers",
+        ]);
+        let output =
+            integration_test_utils::run_delta(GIT_DIFF_FILE_MODE_CHANGE_WITH_DIFF, &config);
+        let output = strip_ansi_codes(&output);
+        let re = Regex::new(r"\n─+\n").unwrap();
+        let output = re.replace(&output, "\n-----\n");
+        assert!(output.contains(
+            "Δ src/script: mode +x
+-----
+
+─────┐
+• 1: │
+─────┘
+-#!/bin/sh
++#!/bin/bash
+"
+        ));
+    }
+
     #[test]
     fn test_hyperlinks_commit_link_format() {
         let config = integration_test_utils::make_config_from_args(&[
@@ -2316,6 +2351,24 @@ new mode 100755
 diff --git a/src/delta.rs b/src/delta.rs
 old mode 100755
 new mode 100644
+";
+
+    const GIT_DIFF_FILE_MODE_CHANGE_UNEXPECTED_BITS: &str = "
+diff --git a/src/delta.rs b/src/delta.rs
+old mode 100700
+new mode 100644
+";
+
+    const GIT_DIFF_FILE_MODE_CHANGE_WITH_DIFF: &str = "
+diff --git a/src/script b/src/script
+old mode 100644
+new mode 100755
+index d00491f..0cfbf08 100644
+--- a/src/script
++++ b/src/script
+@@ -1 +1 @@
+-#!/bin/sh
++#!/bin/bash
 ";
 
     const GIT_DIFF_NO_INDEX_FILENAMES_WITH_SPACES: &str = "