Add check /mnt for readonly before format.

pym/cl_install.py

@@ -1843,6 +1843,10 @@ the system") + " (yes/no)"
                         self.generateHashRoot(stdinRead=stdinReadPwd)
                     addUsers = self.generateHashUsers(stdinRead=stdinReadPwd)
                     migrateUsers = self.getNamesMigrateUsers()
+                mntpath = '/mnt'
+                if not os.access(mntpath,os.W_OK):
+                    raise InstallError(
+                        _("Impossible create directory in '%s'")%mntpath)
                 # cmd options
                 self.printMessageForTest(_("Formating partitions"))
                 targetDistr.performFormat()
@@ -1896,11 +1900,11 @@ the system") + " (yes/no)"
             self.printByResult(False)
         try:
             self.closeClTemplate()
-            if sourceDistr:
+            if sourceDistr and sourceDistr.childs:
                 self.printMessageForTest(_("Releasing source distributive"))
                 sourceDistr.close()
                 self.printByResult(True)
-            if targetDistr:
+            if targetDistr and targetDistr.childs:
                 self.printMessageForTest(_("Unmount target system volume"))
                 targetDistr.close()
                 self.printByResult(True)