Don't fail at upload time when module modifies sys.path

We try to execute all the top level imports but we don't execute
changes to the path so we can get crashes.

Author: hoodmane

src/pyodide/internal/snapshot.ts

@@ -262,8 +262,13 @@ function memorySnapshotDoImports(Module: Module): string[] {
   const deduplicatedModules = [...new Set(importedModules)];
 
   // Import the modules list so they are included in the snapshot.
-  if (deduplicatedModules.length > 0) {
-    simpleRunPython(Module, 'import ' + deduplicatedModules.join(','));
+  for (const mod of deduplicatedModules) {
+    try {
+      simpleRunPython(Module, `import ${mod}`);
+    } catch (e) {
+      continue;
+    }
+    simpleRunPython(Module, `delete ${mod.split(".", 1)[0]}`);
   }
 
   return deduplicatedModules;