--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tests/test-issue6642.t	Thu May 12 13:52:10 2022 +0400
@@ -0,0 +1,37 @@
+hg log --debug shouldn't show different data than {file_*} template keywords
+https://bz.mercurial-scm.org/show_bug.cgi?id=6642
+
+  $ hg init issue6642
+  $ cd issue6642
+
+  $ echo a > a
+  $ hg ci -qAm a
+  $ echo b > b
+  $ hg ci -qAm b
+  $ hg up 0 -q
+  $ echo c > c
+  $ hg ci -qAm c
+  $ hg merge -q
+  $ hg ci -m merge
+
+  $ hg log -GT '{rev} {desc} file_adds: [{file_adds}], file_mods: [{file_mods}], file_dels: [{file_dels}], files: [{files}]\n'
+  @    3 merge file_adds: [], file_mods: [], file_dels: [], files: []
+  |\
+  | o  2 c file_adds: [c], file_mods: [], file_dels: [], files: [c]
+  | |
+  o |  1 b file_adds: [b], file_mods: [], file_dels: [], files: [b]
+  |/
+  o  0 a file_adds: [a], file_mods: [], file_dels: [], files: [a]
+  
+
+  $ hg log -r . --debug | grep files
+  files+:      b (known-bad-output !)
+  [1] (missing-correct-output !)
+  $ hg log -r . --debug -T json | egrep '(added|removed|modified)'
+    "added": ["b"], (known-bad-output !)
+    "added": [], (missing-correct-output !)
+    "modified": [],
+    "removed": [],
+  $ hg log -r . --debug -T xml | grep path
+  <paths>
+  </paths>