BLD: re cythonize files only if we have changed then

Author: jreback

ci/prep_ccache.sh

@@ -6,6 +6,7 @@ if [ "$IRON_TOKEN" ]; then
     pip install -I --allow-external --allow-insecure git+https://github.com/iron-io/iron_cache_python.git@8a451c7d7e4d16e0c3bedffd0f280d5d9bd4fe59#egg=iron_cache
 
 
+    curdir=$(pwd)
     python ci/ironcache/get.py
     ccache -C
 
@@ -22,14 +23,23 @@ if [ "$IRON_TOKEN" ]; then
     fi
 
     # did the last commit change cython files?
-    git diff HEAD~5 | grep diff | grep -P "pyx|pxd"
+    cd $curdir
 
-    if [ "$?" != "0" ]; then
+    echo "diff from HEAD~5"
+    git diff HEAD~5 --numstat
+
+    retval=$(git diff HEAD~5 --numstat | grep -P "pyx|pxd"|wc -l)
+    echo "number of cython files changed: $retval"
+
+    if [ $retval -eq 0 ]
+    then
         # nope, reuse cython files
         echo "Will reuse cached cython file"
         touch "$TRAVIS_BUILD_DIR"/pandas/*.c
         touch "$TRAVIS_BUILD_DIR"/pandas/src/*.c
         touch "$TRAVIS_BUILD_DIR"/pandas/*.cpp
+    else
+        echo "Rebuilding cythonized files"
     fi
 fi