Stop last-modified script over-committing (fixes #549)

Lines may have changed close to the last_modified_at line which would
result in conflicts if using stash/patch applies.

Author: cmbuckley

_ci/last-modified.sh

@@ -11,13 +11,27 @@ $0 ~ "---" && ++count == 2 {
 date="$(date +'%Y-%m-%d %H:%M %z')"
 awk 2>&1 | grep -q includefile && inplace=1 || inplace=0
 
-while read -d $'\0' file; do
+patchdate () {
     if [ $inplace -eq 1 ]; then
-        awk -i inplace -v date="$date" "$awkcmd" "$file"
+        awk -i inplace -v date="$date" "$awkcmd" "$1"
     else
         tmp=$(mktemp)
-        awk -v date="$date" "$awkcmd" "$file" > "$tmp"
-        mv "$tmp" "$file"
+        awk -v date="$date" "$awkcmd" "$1" > "$tmp"
+        mv "$tmp" "$1"
     fi
-    git add "$file" # @todo avoid committing any other changes
+}
+
+while read -d $'\0' file; do
+    # move file out and get rid of unstaged changes
+    tmp=$(mktemp)
+    cp "$file" "$tmp"
+    git restore "$file"
+
+    # patch and add the file
+    patchdate "$file"
+    git add "$file"
+
+    # restore the unstaged changes and reapply the patch
+    mv "$tmp" "$file"
+    patchdate "$file"
 done