Switch to container-based Travis infrastructure

.travis.yml

@@ -1,5 +1,16 @@
 language: python
 
+# Setting sudo to false opts in to Travis-CI container-based builds.
+sudo: false
+
+# The apt packages below are needed for sphinx builds
+addons:
+    apt:
+        packages:
+            - graphviz
+            - texlive-latex-extra
+            - dvipng
+
 python:
     - 2.6
     - 2.7
@@ -65,12 +76,6 @@ before_install:
     - export PATH=/home/travis/miniconda/bin:$PATH
     - conda update --yes conda
 
-    # UPDATE APT-GET LISTINGS
-    - sudo apt-get update
-
-    # DOCUMENTATION DEPENDENCIES
-    - if [[ $SETUP_CMD == build_sphinx* ]]; then sudo apt-get install graphviz texlive-latex-extra dvipng; fi
-
     # Make sure that interactive matplotlib backends work
     - export DISPLAY=:99.0
     - sh -e /etc/init.d/xvfb start

wcsaxes/datasets/__init__.py

@@ -1,6 +1,9 @@
 # Licensed under a 3-clause BSD style license - see LICENSE.rst
 """Downloads the FITS files that are used in image testing and for building documentation.
 """
+
+import time
+
 from astropy.utils.data import download_file
 from astropy.io import fits
 
@@ -11,13 +14,24 @@
            'fetch_bolocam_hdu',
            ]
 
+MAX_RETRIES = 10
+TIME_BETWEEN_RETRIES = 5
 URL = 'http://data.astropy.org/'
 
 
 def fetch_hdu(filename, cache=True):
     """Download a FITS file to the cache and open HDU 0.
     """
-    path = download_file(URL + filename, cache=cache)
+    for retry in range(MAX_RETRIES):
+        try:
+            path = download_file(URL + filename, cache=cache, timeout=30)
+        except:
+            if retry == MAX_RETRIES - 1:
+                raise
+            else:
+                time.sleep(TIME_BETWEEN_RETRIES)
+        else:
+            break
     return fits.open(path)[0]