code-review-difftool: Retain old `extglob` setting

If `extglob` was set, we'd always unset it. Check to see if it's set
before doing anything with it, and then restore it to its original
value.

1 files changed, 9 insertions, 2 deletions

diff --git a/code-review-difftool b/code-review-difftool
index 247586e..10ff89d 100755
--- a/code-review-difftool
+++ b/code-review-difftool
@@ -24,8 +24,15 @@ source "$SCRIPT/code-review-database"
 review_base="$(get_merge_base)"
 
 # Remove dot ranges at the end of a revision as Fugitive doesn't support them.
-shopt -s extglob
+shopt -p extglob
+has_extglob=$?
+
+if [ $has_extglob -ne 0 ]; then
+	shopt -s extglob
+fi
 review_base_without_dots="${review_base%%?(..|...)}"
-shopt -u extglob
+if [ $has_extglob -ne 0 ]; then
+	shopt -u extglob
+fi
 
 vim -c "tabdo Gdiff $review_base_without_dots" -p $(code-review changed-files)