building: util: Only update resources of cached files when necessary.

This fixes #2526. Pyinstaller is updating the resources for python35.dll and makes its signature invalid. This then prevents that dll from being signed with the 'signtool' utility (which then can have more consequences, like the inability to publish the app to a repository where signing is mandatory).

In this commit, the resource update is skipped if it is not necessary, i.e. it is only performed if there have been some redirections or if the dll has been made private.

PyInstaller/building/utils.py

@@ -122,12 +122,15 @@ def applyRedirects(manifest, redirects):
     :return:
     :rtype:
     """
+    redirecting = False
     for binding in redirects:
         for dep in manifest.dependentAssemblies:
             if match_binding_redirect(dep, binding):
                 logger.info("Redirecting %s version %s -> %s",
                             binding.name, dep.version, binding.newVersion)
                 dep.version = binding.newVersion
+                redirecting = True
+    return redirecting
 
 def checkCache(fnm, strip=False, upx=False, dist_nm=None):
     """
@@ -299,7 +302,8 @@ def checkCache(fnm, strip=False, upx=False, dist_nm=None):
                             logger.error("From file %s", cachedfile, exc_info=1)
                         else:
                             # optionally change manifest to private assembly
-                            if CONF.get('win_private_assemblies', False):
+                            private = CONF.get('win_private_assemblies', False)
+                            if private:
                                 if manifest.publicKeyToken:
                                     logger.info("Changing %s into a private assembly",
                                                 os.path.basename(fnm))
@@ -310,14 +314,15 @@ def checkCache(fnm, strip=False, upx=False, dist_nm=None):
                                     # Exclude common-controls which is not bundled
                                     if dep.name != "Microsoft.Windows.Common-Controls":
                                         dep.publicKeyToken = None
-                            applyRedirects(manifest, redirects)
-                            try:
-                                manifest.update_resources(os.path.abspath(cachedfile),
-                                                          [name],
-                                                          [language])
-                            except Exception as e:
-                                logger.error(os.path.abspath(cachedfile))
-                                raise
+                            redirecting = applyRedirects(manifest, redirects)
+                            if redirecting or private:
+                                try:
+                                    manifest.update_resources(os.path.abspath(cachedfile),
+                                                              [name],
+                                                              [language])
+                                except Exception as e:
+                                    logger.error(os.path.abspath(cachedfile))
+                                    raise
 
     if cmd:
         try: