Fix markdown changelog generation test

System tests typically run outside the workspace directory, but they
still have read-only access to the workspace; fix it accordingly.
This test only works on git checkouts, not in tarballs, so skip it
if .git doesn't exist.

.github/workflows/main.yml

@@ -22,7 +22,7 @@ jobs:
         sudo apt install gettext libpcre2-dev python3-pexpect python3-sphinx tmux
         # Generate a locale that uses a comma as decimal separator.
         sudo locale-gen fr_FR.UTF-8
-    # - uses: ./.github/actions/install-sphinx-markdown-builder
+    - uses: ./.github/actions/install-sphinx-markdown-builder
     - name: cmake
       run: |
         mkdir build && cd build

build_tools/release-notes.sh

@@ -11,15 +11,18 @@ mkdir -p "$relnotes_tmp/fake-workspace" "$relnotes_tmp/out"
     cp -r doc_src CONTRIBUTING.rst README.rst "$relnotes_tmp/fake-workspace"
 )
 version=$(sed 's,^fish \(\S*\) .*,\1,; 1q' "$workspace_root/CHANGELOG.rst")
-previous_version=$(awk <"$workspace_root/CHANGELOG.rst" '
-    ( /^fish \S*\.\S*\.\S* \(released .*\)$/ &&
-        NR > 1 &&
-        # Skip tags that have not been created yet..
-        system("git rev-parse --verify >/dev/null --quiet refs/tags/"$2) == 0 \
-    ) {
-        print $2; exit
-    }
-')
+previous_version=$(
+    cd "$workspace_root"
+    awk <CHANGELOG.rst '
+        ( /^fish \S*\.\S*\.\S* \(released .*\)$/ &&
+            NR > 1 &&
+            # Skip tags that have not been created yet..
+            system("git rev-parse --verify >/dev/null --quiet refs/tags/"$2) == 0 \
+        ) {
+            print $2; exit
+        }
+    '
+)
 minor_version=${version%.*}
 changelog_for_this_version=$(awk <"$workspace_root/CHANGELOG.rst" '
     /^===/ { if (v++) { exit } }
@@ -48,7 +51,10 @@ sed -i 1,2d "$relnotes_tmp/out/relnotes.md"
     echo ""
     echo "---"
     echo ""
-    "$workspace_root"/build_tools/list_committers_since.fish "$previous_version"
+    (
+        cd "$workspace_root"
+        build_tools/list_committers_since.fish "$previous_version"
+    )
     cat <<EOF
 
 ---

tests/checks/sphinx-markdown-changelog.fish

@@ -2,8 +2,12 @@
 #REQUIRES: command -v sphinx-build
 #REQUIRES: python -c 'import sphinx_markdown_builder'
 
-set -l build_script (status dirname)/../../build_tools/release-notes.sh
-$build_script -q >relnotes.md
+set -l workspace_root (status dirname)/../..
+if not test -e $workspace_root/.git
+    return
+end
+
+$workspace_root/build_tools/release-notes.sh -q >relnotes.md
 or echo "Failed to build Markdown release notes."
-sed -n 1p relnotes.md
-# CHECK: ## fish {{.*}} (released {{.*}})
+sed -n 1p relnotes.md | grep -q '^## fish \S* (released .*)'
+or echo "Unexpected changelog title"