v1.94.3.0 fix(ship-preflight): stop when origin's default branch can't be read (#3718 follow-up) (#3913)

* fix(ship-preflight): stop when ls-remote origin HEAD fails instead of guessing the default branch

Co-authored-by: capy-ai[bot] <230910855+capy-ai[bot]@users.noreply.github.com>

* fix(ship-preflight): a remote HEAD with no branch falls back to the default-base order; docs name the whole order

Co-authored-by: capy-ai[bot] <230910855+capy-ai[bot]@users.noreply.github.com>

* changelog: say when the default-base order still reads the local origin/HEAD

Co-authored-by: capy-ai[bot] <230910855+capy-ai[bot]@users.noreply.github.com>

---------

Co-authored-by: capy-ai[bot] <230910855+capy-ai[bot]@users.noreply.github.com>

docs/eval-calls.md

@@ -22,7 +22,9 @@ dropped), so a command with quotes or `$` never passes through a shell string;
 
 1. `--plan-file <file>`: an operator-given file, read from disk.
 2. Otherwise `price_file` in `.gstack/pregate.json` as committed on
-   `origin/<base>` (`--base`, default origin/HEAD's branch): a repo-relative
+   `origin/<base>` (`--base`, default origin/HEAD's branch unless it names the
+   checked-out branch, its upstream or HEAD's commit, then the PR's base, the
+   remote's live HEAD, `main` or `master`): a repo-relative
    path whose bytes are read from the **HEAD commit** (`git show HEAD:<path>`),
    never from the working tree.
 

docs/eval-models.md

@@ -66,7 +66,9 @@ unless the command says it is a smoke run.
 ## Which copy is read
 
 By default the reviewed copy is read: `git show origin/<base>:.gstack/eval-models.json`
-(`--base`, default origin/HEAD's branch). A branch cannot loosen the rules it
+(`--base`, default origin/HEAD's branch unless it names the checked-out branch,
+its upstream or HEAD's commit, then the PR's base, the remote's live HEAD, `main`
+or `master`). A branch cannot loosen the rules it
 is checked against. When the working-tree copy differs, an
 `EVAL_MODELS_NOTE:` line says so. `--models-from head` lints with the working-tree copy
 instead. Use it for the PR that adds or changes the file; the source label