Check if tmp folder already exists during pma upgrade.

src/deb/hestia/postinst

@@ -35,8 +35,10 @@ if [ "$DB_SYSTEM" = 'mysql' ]; then
     sed -i "s|define('TEMP_DIR', './tmp/');|define('TEMP_DIR', '/var/lib/phpmyadmin/tmp/');|" /usr/share/phpmyadmin/libraries/vendor_config.php
 
     # Create temporary folder and change permission
-    mkdir /usr/share/phpmyadmin/tmp
-    chmod 777 /usr/share/phpmyadmin/tmp
+    if [ ! -d /usr/share/phpmyadmin/tmp]; then
+        mkdir /usr/share/phpmyadmin/tmp
+        chmod 777 /usr/share/phpmyadmin/tmp
+    fi
 
     # Clear Up
     rm -fr phpMyAdmin-$pma_v-all-languages
@@ -45,10 +47,10 @@ fi
 
 # Add amd64 to repositorys to prevent notifications - https://goo.gl/hmsSV7
 if ! grep -q 'amd64' /etc/apt/sources.list.d/nginx.list; then
-    sed s/deb/"deb [arch=amd64]"/g /etc/apt/sources.list.d/nginx.list
+    sed -i s/deb/"deb [arch=amd64]"/g /etc/apt/sources.list.d/nginx.list
 fi
 if ! grep -q 'amd64' /etc/apt/sources.list.d/mariadb.list; then
-    sed s/deb/"deb [arch=amd64]"/g /etc/apt/sources.list.d/mariadb.list
+    sed -i s/deb/"deb [arch=amd64]"/g /etc/apt/sources.list.d/mariadb.list
 fi
 
 # Fix named rule for AppArmor - https://goo.gl/SPqHdq