fix(push): report modified patches in output

Somewhere along the way, `stg push` stopped correctly reporting to the
user when the pushed patch(es) were updated during the push.

With this change, when a push causes a new commit to be made for a
patch, that patch will be reported in the user-facing output as
"(modified)" unless a superceding "(empty)", "(merged)", or "(conflict)"
status applies.

Fixes: #464

Author: jpgrayson

src/stack/transaction/mod.rs

@@ -1090,7 +1090,6 @@ impl<'repo> StackTransaction<'repo> {
                             conflicts: false,
                         })?;
                         self.current_tree_id = tree_id;
-                        push_status = PushStatus::Modified;
                         tree_id
                     }
                     Ok(false) => {
@@ -1131,10 +1130,12 @@ impl<'repo> StackTransaction<'repo> {
                 // execute() performs the checkout. Setting the transaction head
                 // here ensures that the real stack top will be checked-out.
                 self.updated_head = Some(commit.clone());
-            } else if push_status != PushStatus::AlreadyMerged
-                && new_tree_id == new_parent_ref.tree()
-            {
-                push_status = PushStatus::Empty;
+            } else if push_status != PushStatus::AlreadyMerged {
+                if new_tree_id == new_parent_ref.tree() {
+                    push_status = PushStatus::Empty;
+                } else {
+                    push_status = PushStatus::Modified;
+                }
             }
 
             self.updated_patches

t/t1204-push-updated.sh

@@ -0,0 +1,60 @@
+#!/bin/sh
+
+test_description='Test push that must be updated due to previous patch with same changes.'
+
+. ./test-lib.sh
+
+test_expect_success 'Setup patches' '
+    echo "foo" >foo.txt &&
+    git add foo.txt &&
+    git commit -m "initial" &&
+    stg init &&
+    cat >foo.txt <<-\EOF &&
+	foo
+	.
+	bar
+	.
+	EOF
+    stg new -rm "p0" &&
+    cat >foo.txt <<-\EOF &&
+	foo
+	.
+	BAR
+	bar
+	.
+	baz
+	EOF
+    stg new -rm "p1"
+'
+
+test_expect_success 'Push unmodified patches' '
+    stg pop -a &&
+    stg push -a >out &&
+    cat >expected <<-\EOF &&
+	+ p0
+	> p1
+	EOF
+    test_cmp expected out
+'
+
+test_expect_success 'Move hunk to p0' '
+    stg goto p0 &&
+    cat >foo.txt <<-\EOF &&
+	foo
+	.
+	BAR
+	bar
+	.
+	EOF
+    stg refresh
+'
+
+test_expect_success 'Push indicates p1 was modified' '
+    cat >expected <<-\EOF &&
+	> p1 (modified)
+	EOF
+    stg push p1 >out &&
+    test_cmp expected out
+'
+
+test_done