commit: fix unmodified message detection for the "--- >8 ----" magic

We need the raw editortext to be compared with the templatetext.

mercurial/cmdutil.py

@@ -2772,14 +2772,15 b' def commitforceeditor(repo, ctx, subs, f'
 
     editortext = repo.ui.edit(committext, ctx.user(), ctx.extra(),
                         editform=editform, pending=pending)
+    text = editortext
 
     # strip away anything below this special string (used for editors that want
     # to display the diff)
-    stripbelow = re.search(_linebelow, editortext, flags=re.MULTILINE)
+    stripbelow = re.search(_linebelow, text, flags=re.MULTILINE)
     if stripbelow:
-        editortext = editortext[:stripbelow.start()]
-
-    text = re.sub("(?m)^HG:.*(\n|$)", "", editortext)
+        text = text[:stripbelow.start()]
+
+    text = re.sub("(?m)^HG:.*(\n|$)", "", text)
     os.chdir(olddir)
 
     if finishdesc:

tests/test-commit.t

@@ -712,6 +712,9 b' test that text below the --- >8 --- spec'
   > EOF
   $ echo foo2 > foo2
   $ hg add foo2
+  $ HGEDITOR="sh $TESTTMP/notouching.sh" hg ci
+  abort: commit message unchanged
+  [255]
   $ HGEDITOR="sh $TESTTMP/lowercaseline.sh" hg ci
   first line
   HG: this is customized commit template