static-web-server: handle files from nix store epoch+1 (#498890)

pkgs/by-name/st/static-web-server/include-unix-time-plus-one.diff

@@ -0,0 +1,13 @@
+diff --git a/src/response.rs b/src/response.rs
+index 25da3d3..92d6203 100644
+--- a/src/response.rs
++++ b/src/response.rs
+@@ -42,7 +42,7 @@ pub(crate) fn response_body(
+     let modified = meta
+         .modified()
+         .ok()
+-        .filter(|&t| t != std::time::UNIX_EPOCH)
++        .filter(|&t| t > (std::time::UNIX_EPOCH + std::time::Duration::from_secs(1)))
+         .map(LastModified::from);
+ 
+     match conditionals.check(modified) {

pkgs/by-name/st/static-web-server/package.nix

@@ -18,9 +18,14 @@ rustPlatform.buildRustPackage (finalAttrs: {
 
   cargoHash = "sha256-rNrGlgUvPezX7RnKhprRjl9DiJ/Crt4phmxnfY9tNXA=";
 
-  # Some tests rely on timestamps newer than 18 Nov 1974 00:00:00
-  preCheck = ''
-    find docker/public -exec touch -m {} \;
+  # static-web-server already has special handling for files with modification
+  # time = unix epoch, but the nix store is unix epoch + 1 second.
+  patches = [ ./include-unix-time-plus-one.diff ];
+
+  # Some tests which implicitly relied on the above behavior now break.  Force
+  # an mtime update to fix.
+  postUnpack = ''
+    find . -exec touch -m {} +
   '';
 
   # Need to copy in the systemd units for systemd.packages to discover them