diff --git a/.github/workflows/mononoke_linux.yml b/.github/workflows/mononoke_linux.yml
index 2f0538007ba1f..23f14dafbf074 100644
--- a/.github/workflows/mononoke_linux.yml
+++ b/.github/workflows/mononoke_linux.yml
@@ -8,12 +8,7 @@
 name: Mononoke Linux
 
 on:
-  push:
-    branches:
-    - main
-  pull_request:
-    branches:
-    - main
+  workflow_dispatch
 
 permissions:
   contents: read  #  to fetch code (actions/checkout)
diff --git a/eden/scm/build.py b/eden/scm/build.py
index e5bc3576ee3b7..f48eb6141fcad 100755
--- a/eden/scm/build.py
+++ b/eden/scm/build.py
@@ -461,6 +461,9 @@ def cargo_env(args):
         env["OPENSSL_DIR"] = str(openssl)
         env.pop("OPENSSL_STATIC", None)
     env["RUSTFLAGS"] = (env.get("RUSTFLAGS", "") + " -Anon_local_definitions").strip()
+    # Allow nightly features (smallvec specialization, once_cell_try) on stable Rust.
+    # Required for `make oss` / cargo oss builds. Buck builds use nightly toolchain internally.
+    env.setdefault("RUSTC_BOOTSTRAP", "1")
     set_windows_python_path(env, args.python)
     return env
 
diff --git a/eden/scm/sapling/util.py b/eden/scm/sapling/util.py
index 04c3b5f93e17c..0e2bb78d3c7af 100644
--- a/eden/scm/sapling/util.py
+++ b/eden/scm/sapling/util.py
@@ -491,10 +491,16 @@ def versionagedays() -> int:
     """Returns approximate age in days of the current version, or 0 if not available."""
     try:
         v = version()
-        parts = remod.split("_", v)
-        approxbuilddate = datetime.datetime.strptime(parts[1], "%Y%m%d")
-        now = datetime.datetime.now()
-        return (now - approxbuilddate).days
+        parts = remod.split(r"[_\.\-+]", v)
+        for part in parts:
+            if len(part) == 8 and part.isdigit():
+                try:
+                    approxbuilddate = datetime.datetime.strptime(part, "%Y%m%d")
+                    now = datetime.datetime.now()
+                    return max(0, (now - approxbuilddate).days)
+                except ValueError:
+                    pass
+        return 0
     except Exception:
         return 0