Fix requirements update

Sphinx 1.5 fails with current pbr (needs new pbr release, see change
I52d45fa0a0d42de690d3a492068f7bb03483a224.

For now, set warnerrors to False to be able to use this.

Also, remove duplicate requirements line.

Also, update to new sphinx version to show that this works.

This is in reaction to the failure in
Ia184446fe34c49a48ca079c828157ea34e662d4b.

Change-Id: I9e7261c4124b71eeb6bddd9e21747b61bbdc16fa

requirements.txt

@@ -7,4 +7,3 @@ pbr>=1.8 # Apache-2.0
 PyYAML>=3.10.0 # MIT
 flake8<2.6.0,>=2.5.4 # MIT
 six>=1.9.0 # MIT
-oslosphinx>=4.7.0 # Apache-2.0

setup.cfg

@@ -42,7 +42,8 @@ mapping_file = babel.cfg
 output_file = diskimage_builder/locale/diskimage_builder.pot
 
 [pbr]
-warnerrors = True
+# TODO(jaegerandi): Set to True once pbr 1.11.0 is out.
+warnerrors = False
 
 [update_catalog]
 domain = diskimage_builder

test-requirements.txt

@@ -7,7 +7,7 @@ oslotest>=1.10.0 # Apache-2.0
 testrepository>=0.0.18 # Apache-2.0/BSD
 
 # Doc requirements
-sphinx!=1.3b1,<1.4,>=1.2.1 # BSD
+sphinx>=1.5.1 # BSD
 oslosphinx>=4.7.0 # Apache-2.0
 
 # releasenotes