double-check that package is precompiled after waiting

src/API.jl

@@ -1595,9 +1595,17 @@ function maybe_cachefile_lock(f, pkg::Base.PkgId, srcpath::String, pkgspidlocked
         else
             "machine (hostname: $hostname, pid: $pid)"
         end
-        # wait until the lock is available, but don't actually acquire it
-        # returning nothing indicates a process waited for another
-        return FileWatching.mkpidlock(Returns(nothing), pidfile)
+        # wait until the lock is available
+        FileWatching.mkpidlock(pidfile) do
+            # double-check in case the other process crashed or the lock expired
+            if Base.isprecompiled(pkg)
+                # returning nothing indicates a process waited for another
+                return nothing
+            else
+                delete!(pkgspidlocked, pkg)
+                return f()
+            end
+        end
     end
     return cachefile
 end