fix: create header file manually to avoid mode 600

apatch

@@ -44,7 +44,8 @@ abuild clean fetch unpack default_prepare
 startdir="$PWD"
 srcdir="$startdir/src"
 . APKBUILD
-test -n "$builddir" || builddir="$srcdir/$pkgname-$pkgver"
+unset -f grep cut head git rm mv
+[ -n "$builddir" ] || builddir="$srcdir/$pkgname-$pkgver"
 
 patchpath="$startdir/$1"
 
@@ -67,7 +68,7 @@ if [ -f "$patchpath" ]; then
   msg "patch exists, trying to extract existing message"
   # try to extract the original header from the patch
   patch_start=$(grep -En '^(diff --git|--- )' "$patchpath" | cut -d: -f1 | head -n 1)
-  header_file="$(mktemp -t apatch.XXXXXX)"
+  header_file="/tmp/$(mktemp -u apatch.XXXXXX)"
   head -n $(( patch_start - 1 )) "$patchpath" > "$header_file"
 fi