[ONE Original Android Development] Genericxx:
I've grabbed a logcat while cm filemanager tries to save the file. Maybe it helps out...

11-09 08:36:36.343 E/SpannableStringBuilder(9710): SPAN_EXCLUSIVE_EXCLUSIVE spans cannot have a zero length
11-09 08:36:36.343 E/SpannableStringBuilder(9710): SPAN_EXCLUSIVE_EXCLUSIVE spans cannot have a zero length
11-09 08:36:36.430 E/SpannableStringBuilder(9710): SPAN_EXCLUSIVE_EXCLUSIVE spans cannot have a zero length
11-09 08:36:36.430 E/SpannableStringBuilder(9710): SPAN_EXCLUSIVE_EXCLUSIVE spans cannot have a zero length
11-09 08:36:38.077 E/EditorActivity(9710): The file wasn't written.
11-09 08:36:38.077 E/EditorActivity(9710): java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String com.cyanogenmod.filemanager.model.MountPoint.getMountPoint()' on a null object reference
11-09 08:36:38.077 E/EditorActivity(9710): at com.cyanogenmod.filemanager.commands.shell.Shell.checkStdErr(Shell.java:141)
11-09 08:36:38.077 E/EditorActivity(9710): at com.cyanogenmod.filemanager.commands.shell.SuperuserShell.checkStdErr(SuperuserShell.java:81)
11-09 08:36:38.077 E/EditorActivity(9710): at com.cyanogenmod.filemanager.console.shell.ShellConsole.syncExecute(ShellConsole.java:721)
11-09 08:36:38.077 E/EditorActivity(9710): at com.cyanogenmod.filemanager.console.shell.ShellConsole.execute(ShellConsole.java:541)
11-09 08:36:38.077 E/EditorActivity(9710): at com.cyanogenmod.filemanager.console.shell.ShellConsole.execute(ShellConsole.java:486)
11-09 08:36:38.077 E/EditorActivity(9710): at com.cyanogenmod.filemanager.util.CommandHelper.writableExecute(CommandHelper.java:2050)
11-09 08:36:38.077 E/EditorActivity(9710): at com.cyanogenmod.filemanager.util.CommandHelper.write(CommandHelper.java:1581)
11-09 08:36:38.077 E/EditorActivity(9710): at com.cyanogenmod.filemanager.activities.EditorActivity.syncWrite(EditorActivity.java:1629)
11-09 08:36:38.077 E/EditorActivity(9710): at com.cyanogenmod.filemanager.activities.EditorActivity.ensureSyncWrite(EditorActivity.java:1558)
11-09 08:36:38.077 E/EditorActivity(9710): at com.cyanogenmod.filemanager.activities.EditorActivity.checkAndWrite(EditorActivity.java:1524)
11-09 08:36:38.077 E/EditorActivity(9710): at com.cyanogenmod.filemanager.activities.EditorActivity.onActionBarItemClick(EditorActivity.java:966)
11-09 08:36:38.077 E/EditorActivity(9710): at java.lang.reflect.Method.invoke(Native Method)
11-09 08:36:38.077 E/EditorActivity(9710): at android.view.View$DeclaredOnClickListener.onClick(View.java:4447)
11-09 08:36:38.077 E/EditorActivity(9710): at android.view.View.performClick(View.java:5198)
11-09 08:36:38.077 E/EditorActivity(9710): at android.view.View$PerformClick.run(View.java:21150)
11-09 08:36:38.077 E/EditorActivity(9710): at android.os.Handler.handleCallback(Handler.java:739)
11-09 08:36:38.077 E/EditorActivity(9710): at android.os.Handler.dispatchMessage(Handler.java:95)
11-09 08:36:38.077 E/EditorActivity(9710): at android.os.Looper.loop(Looper.java:148)
11-09 08:36:38.077 E/EditorActivity(9710): at android.app.ActivityThread.main(ActivityThread.java:5466)
11-09 08:36:38.077 E/EditorActivity(9710): at java.lang.reflect.Method.invoke(Native Method)
11-09 08:36:38.077 E/EditorActivity(9710): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
11-09 08:36:38.077 E/EditorActivity(9710): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)