aiFeatures-mjs.patch not (correctly) imported/applied

[iskunk]

(Reposted from the desktop repo bug)

This concerns src/browser/components/preferences/config/aiFeatures-mjs.patch. I've noticed that after running surfer import, even though I see this...

[...]
  [FINISH] Apply /tmp/zen-browser-desktop/src/browser/components/places/content/editBookmark-js.patch
  [FINISH] Apply /tmp/zen-browser-desktop/src/browser/components/places/content/editBookmarkPanel-inc-xhtml.patch
  [FINISH] Apply /tmp/zen-browser-desktop/src/browser/components/preferences/config/aiFeatures-mjs.patch    <-----
  [FINISH] Apply /tmp/zen-browser-desktop/src/browser/components/preferences/dialogs/syncChooseWhatToSync-js.patch
  [FINISH] Apply /tmp/zen-browser-desktop/src/browser/components/preferences/dialogs/syncChooseWhatToSync-xhtml.patch
[...]

...the file it targets shows no modifications:

$ git status browser/components/preferences/config/aiFeatures.mjs 
On branch zen_browser
nothing to commit, working tree clean

I looked at the Git patching code in surfer. I see that it first tries to reverse-apply the patch---presumably in case the patch had previously been applied, in any event ignoring errors---and then applies the patch normally.

Well, when I tried that process manually, I got an odd result...

build@xtradeb-resolute-con:/tmp/zen-browser-desktop/engine$ git apply -R -v ../src/browser/components/preferences/config/aiFeatures-mjs.patch 
Checking patch browser/components/preferences/config/aiFeatures.mjs...
Hunk #1 succeeded at 1178 (offset -544 lines).
Applied patch browser/components/preferences/config/aiFeatures.mjs cleanly.

build@xtradeb-resolute-con:/tmp/zen-browser-desktop/engine$ git apply -v ../src/browser/components/preferences/config/aiFeatures-mjs.patch 
Checking patch browser/components/preferences/config/aiFeatures.mjs...
Hunk #1 succeeded at 1178 (offset 544 lines).
Applied patch browser/components/preferences/config/aiFeatures.mjs cleanly.

build@xtradeb-resolute-con:/tmp/zen-browser-desktop/engine$ git diff browser/components/preferences/config/aiFeatures.mjs
(no output)

I notice that the patch diff is surrounded by a stack of brackets and braces. I think this is a case where the patch needs to be generated with more lines of context than the default, so that the patching program doesn't get confused.

[iskunk]

On a separate note, these two patches similarly appear to have no effect, but for a different reason:

src/external-patches/firefox/bug_2013682_allow_stacking_contexts_to_be_promoted.patch
src/external-patches/firefox/session_store_use_size_hint/D247145.patch

The Firefox source (I'm working with 150.0.3) appears to have these already applied upstream. So surfer backs them out, and then puts them back in, with no net changes.

[iskunk]

In 151.0.2 / 1.20.1b, this one appears to be already applied upstream:

src/external-patches/firefox/gh-12979_clip_dirty_rect_to_device_size.patch

The aforementioned session_store_use_size_hint/D247145.patch is no longer present.