minor #3785 ensure that destination directories don't exist before creating them (xabbuh)

This PR was merged into the 2.3 branch.

Discussion
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ensure that destination directories don't exist before creating them

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | all
| Fixed tickets |

The ``install.sh`` script fails if you run it multiple times (e.g. to update the bundle and CMF docs).

Commits
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de7d206 ensure that destination directories don't exist before creating them

Author: weaverryan

install.sh

@@ -8,6 +8,7 @@ function sparse_checkout {
     git remote add -f origin http://github.com/$1/$2
     echo Resources/doc > .git/info/sparse-checkout
     git checkout master
+    rm -rf ../bundles/$2
     mv Resources/doc ../bundles/$2
     cd ..
     rm -rf sparse_checkout
@@ -18,5 +19,6 @@ sparse_checkout sensiolabs SensioGeneratorBundle
 sparse_checkout doctrine DoctrineFixturesBundle
 sparse_checkout doctrine DoctrineMigrationsBundle
 sparse_checkout doctrine DoctrineMongoDBBundle
+rm -rf cmf
 git clone http://github.com/symfony-cmf/symfony-cmf-docs cmf