Make sure mod time is not > install time, when installing.

By making them always exactly equal.  This includes installs for updates.

Fixes #1723

modules/remoteScript.js

@@ -332,12 +332,9 @@ RemoteScript.prototype.install = function(aOldScript, aOnlyDependencies) {
     this._tempDir.moveTo(GM_util.scriptDir(), this._baseName);
     this._tempDir = null;
 
-    // Since we moved the file, it's modtime changed, update the script:
-    this.script.setModTimeFromFile();
-    // Let the config know the base/file name has changed to its real value now.
-    GM_config._changed(this.script, 'modified', this.script.id);
-
+    this.script.fixTimestampsOnInstall();
     this.script.checkConfig();
+    this.script._changed('modified');
 
     // Let the user know we're all done.
     GM_notification(

modules/script.js

@@ -259,8 +259,9 @@ Script.prototype.setFilename = function(aBaseName, aFileName) {
   if (!this._downloadURL) this._downloadURL = this.fileURL;
 };
 
-Script.prototype.setModTimeFromFile = function() {
+Script.prototype.fixTimestampsOnInstall = function() {
   this._modifiedTime = this.file.lastModifiedTime;
+  this._installTime = this.file.lastModifiedTime;
 };
 
 Script.prototype._loadFromConfigNode = function(node) {