dirstate-entry: add `modified` property

dirstate-entry: add `modified` property

This was already done in the Rust implementation and is a useful primitive.
The C implementation had this called `merged`, but wasn't used anywhere.

It will be used in the next changeset.

--- a/mercurial/cext/parsers.c	Mon Dec 19 16:22:01 2022 +0100
+++ b/mercurial/cext/parsers.c	Mon May 02 11:40:33 2022 +0200
@@ -177,7 +177,7 @@
 	        (dirstate_flag_p1_tracked | dirstate_flag_p2_info));
 }
 
-static inline bool dirstate_item_c_merged(dirstateItemObject *self)
+static inline bool dirstate_item_c_modified(dirstateItemObject *self)
 {
 	return ((self->flags & dirstate_flag_wc_tracked) &&
 	        (self->flags & dirstate_flag_p1_tracked) &&
@@ -195,7 +195,7 @@
 {
 	if (dirstate_item_c_removed(self)) {
 		return 'r';
-	} else if (dirstate_item_c_merged(self)) {
+	} else if (dirstate_item_c_modified(self)) {
 		return 'm';
 	} else if (dirstate_item_c_added(self)) {
 		return 'a';
@@ -642,9 +642,9 @@
 	}
 };
 
-static PyObject *dirstate_item_get_merged(dirstateItemObject *self)
+static PyObject *dirstate_item_get_modified(dirstateItemObject *self)
 {
-	if (dirstate_item_c_merged(self)) {
+	if (dirstate_item_c_modified(self)) {
 		Py_RETURN_TRUE;
 	} else {
 		Py_RETURN_FALSE;
@@ -709,7 +709,7 @@
      NULL},
     {"added", (getter)dirstate_item_get_added, NULL, "added", NULL},
     {"p2_info", (getter)dirstate_item_get_p2_info, NULL, "p2_info", NULL},
-    {"merged", (getter)dirstate_item_get_merged, NULL, "merged", NULL},
+    {"modified", (getter)dirstate_item_get_modified, NULL, "modified", NULL},
     {"from_p2", (getter)dirstate_item_get_from_p2, NULL, "from_p2", NULL},
     {"maybe_clean", (getter)dirstate_item_get_maybe_clean, NULL, "maybe_clean",
      NULL},
@@ -1187,7 +1187,7 @@
 void manifest_module_init(PyObject *mod);
 void revlog_module_init(PyObject *mod);
 
-static const int version = 20;
+static const int version = 21;
 
 static void module_init(PyObject *mod)
 {

--- a/mercurial/policy.py	Mon Dec 19 16:22:01 2022 +0100
+++ b/mercurial/policy.py	Mon May 02 11:40:33 2022 +0200
@@ -76,7 +76,7 @@
     ('cext', 'bdiff'): 3,
     ('cext', 'mpatch'): 1,
     ('cext', 'osutil'): 4,
-    ('cext', 'parsers'): 20,
+    ('cext', 'parsers'): 21,
 }
 
 # map import request to other package or module

--- a/mercurial/pure/parsers.py	Mon Dec 19 16:22:01 2022 +0100
+++ b/mercurial/pure/parsers.py	Mon May 02 11:40:33 2022 +0200
@@ -435,6 +435,11 @@
         return self._wc_tracked and not (self._p1_tracked or self._p2_info)
 
     @property
+    def modified(self):
+        """True if the file has been modified"""
+        return self._wc_tracked and self._p1_tracked and self._p2_info
+
+    @property
     def maybe_clean(self):
         """True if the file has a chance to be in the "clean" state"""
         if not self._wc_tracked:

--- a/rust/hg-cpython/src/dirstate/item.rs	Mon Dec 19 16:22:01 2022 +0100
+++ b/rust/hg-cpython/src/dirstate/item.rs	Mon May 02 11:40:33 2022 +0200
@@ -151,6 +151,10 @@
         Ok(self.entry(py).get().added())
     }
 
+    @property
+    def modified(&self) -> PyResult<bool> {
+        Ok(self.entry(py).get().modified())
+    }
 
     @property
     def p2_info(&self) -> PyResult<bool> {