fix(circleci): cache git-annex installation

Author: oesteban

.circleci/config.yml

@@ -32,21 +32,26 @@ jobs:
             pip install datalad
             pip install "setuptools>=27.0" twine
 
-      - save_cache:
-          key: deps-v2-{{ checksum "/tmp/src/templateflow/requirements.txt"}}-{{ epoch }}
-          paths:
-            - "/opt/circleci/.pyenv/versions/3.5.2"
-            - "/tmp/data/templateflow"
-
       - run:
           name: Install git and git-annex
           command: |
-            wget -O- http://neuro.debian.net/lists/trusty.us-ca.full | sudo tee /etc/apt/sources.list.d/neurodebian.sources.list
-            sudo apt-key adv --recv-keys --keyserver hkp://pool.sks-keyservers.net:80 0xA5D32F012649A5A9
-            sudo apt update && sudo apt-get install -y --no-install-recommends git-annex-standalone
+            if [[ ! -d "/usr/lib/git-annex.linux" || ! -e "/usr/bin/git-annex-shell" ]]; then
+              wget -O- http://neuro.debian.net/lists/trusty.us-ca.full | sudo tee /etc/apt/sources.list.d/neurodebian.sources.list
+              sudo apt-key adv --recv-keys --keyserver hkp://pool.sks-keyservers.net:80 0xA5D32F012649A5A9
+              sudo apt update && sudo apt-get install -y --no-install-recommends git-annex-standalone
+            fi
             git config --global user.name "First Last"
             git config --global user.email "[email protected]"
 
+      - save_cache:
+          key: deps-v2-{{ checksum "/tmp/src/templateflow/requirements.txt"}}-{{ epoch }}
+          paths:
+            - "/opt/circleci/.pyenv/versions/3.5.2"
+            - "/tmp/data/templateflow"
+            - "/usr/lib/git-annex.linux"
+            - "/usr/bin/git-annex"
+            - "/usr/bin/git-annex-shell"
+
       - run:
           name: Run tests (w/o DataLad)
           environment: