MAINT: timestamp nightlies

* as outlined in MacPythongh-77, downstream projects will have
a hard time automatically downloading our most recently
"nightly" (actually weekly) wheel uploads if we don't
add a timestamp of sorts

* this patch attempts to "borrow" the machinery added by
Matti in `https://github.com/MacPython/numpy-wheels/pull/84`
for this purpose

Author: tylerjereddy

.travis.yml

@@ -120,6 +120,8 @@ after_success:
     # used in Travis CI config, originally
     # generated at anaconda.org for scipy-wheels-nightly
     - if [ "$TRAVIS_EVENT_TYPE" == "cron" ]; then
+          source extra_functions.sh;
+          for f in wheelhouse/*.whl; do rename_wheel $f; done;
           ANACONDA_ORG="scipy-wheels-nightly";
           pip install git+https://github.com/Anaconda-Server/anaconda-client;
           anaconda -t ${SCIPY_WHEELS_NIGHTLY} upload --force -u ${ANACONDA_ORG} ${TRAVIS_BUILD_DIR}/wheelhouse/*.whl;

extra_functions.sh

@@ -0,0 +1,14 @@
+function rename_wheel {
+    # Call with a name like scipy-1.5.0.dev0+58dbafa-cp37-cp37m-linux_x86_64.whl
+
+    # Add a date after the dev0+ and before the hash in yyymmddHHMMSS format
+    # so pip will pick up the newest build. Try a little to make sure
+    # - the first part ends with 'dev0+'
+    # - the second part starts with a lower case alphanumeric then a '-'
+    # if those conditions are not met, the name will be returned as-is
+
+    newname=$(echo "$1" | sed "s/\(.*dev0+\)\([a-z0-9]*-.*\)/\1$(date '+%Y%m%d%H%M%S_')\2/")
+    if [ "$newname" != "$1" ]; then
+        mv $1 $newname
+    fi
+}