update/patch: avoid applying patches directly in build repos

Switching branches and applying patches in the build repos will
unnecessarily touch many files, causing rebuilds of packages that didn't
really change; furthermore, it is filling the reflog with many entries.

Don't ever switch to base branch in the build repos and apply patches in
a temporary clone to avoid these issues.

In addition, GPG signing is generally disabled in the build repos to
override potential global configuration (as signing doesn't make sense and
will slow down rebases).

scripts/patch.sh

@@ -5,19 +5,27 @@ shopt -s nullglob
 
 . "$GLUONDIR"/scripts/modules.sh
 
+TMPDIR="$GLUON_BUILDDIR"/tmp
+
+mkdir -p "$TMPDIR"
+
+PATCHDIR="$TMPDIR"/patching
+trap 'rm -rf "$PATCHDIR"' EXIT
+
 for module in $GLUON_MODULES; do
 	echo "--- Patching module '$module' ---"
 
-	cd "$GLUONDIR"/$module
-	git checkout -B patching base
+	git clone -s -b base --single-branch "$GLUONDIR"/$module "$PATCHDIR" 2>/dev/null
 
+	cd "$PATCHDIR"
 	for patch in "$GLUONDIR"/patches/$module/*.patch; do
-		if ! git -c user.name='Gluon Patch Manager' -c user.email='gluon@void.example.com' -c commit.gpgsign=false am --whitespace=nowarn --committer-date-is-author-date "$patch"; then
-			git am --abort
-			git checkout patched
-			git branch -D patching
-			exit 1
-		fi
+		git -c user.name='Gluon Patch Manager' -c user.email='gluon@void.example.com' -c commit.gpgsign=false am --whitespace=nowarn --committer-date-is-author-date "$patch"
 	done
-	git branch -M patched
+
+	cd "$GLUONDIR"/$module
+	git fetch "$PATCHDIR" 2>/dev/null
+	git checkout -B patched FETCH_HEAD
+	git submodule update --init --recursive
+
+	rm -rf "$PATCHDIR"
 done

scripts/update.sh

@@ -14,8 +14,7 @@ for module in $GLUON_MODULES; do
 	mkdir -p "$GLUONDIR"/$module
 	cd "$GLUONDIR"/$module
 	git init
+	git config commit.gpgsign false
 
-	git checkout $commit 2>/dev/null || git fetch $repo $branch
-	git checkout -B base $commit
-	git submodule update --init --recursive
+	git branch -f base $commit 2>/dev/null || git fetch -f $repo $branch:base
 done