Resolved issues of py-pillow, py-scipy and binutils dependencies. Resolves #1506

py-pillow: Remove version dependency on binutils@2.25.  In tests, it works just fine with binutils@2.26.

Fixed flake8 issues.

var/spack/repos/builtin/packages/binutils/package.py

@@ -31,9 +31,8 @@ class Binutils(Package):
     homepage = "http://www.gnu.org/software/binutils/"
     url      = "https://ftp.gnu.org/gnu/binutils/binutils-2.25.tar.bz2"
 
-    # 2.26 is incompatible with py-pillow build for some reason.
     version('2.26', '64146a0faa3b411ba774f47d41de239f')
-    version('2.25', 'd9f3303f802a5b6b0bb73a335ab89d66', preferred=True)
+    version('2.25', 'd9f3303f802a5b6b0bb73a335ab89d66')
     version('2.24', 'e0f71a7b2ddab0f8612336ac81d9636b')
     version('2.23.2', '4f8fa651e35ef262edc01d60fb45702e')
     version('2.20.1', '2b9dc8f2b7dbd5ec5992c6e29de0b764')

var/spack/repos/builtin/packages/py-pillow/package.py

@@ -32,7 +32,8 @@ class PyPillow(Package):
     capabilities."""
 
     homepage = "https://python-pillow.org/"
-    url      = "https://pypi.python.org/packages/source/P/Pillow/Pillow-3.0.0.tar.gz"
+    url = "https://pypi.python.org/packages/source" + \
+        "/P/Pillow/Pillow-3.0.0.tar.gz"
 
     # TODO: This version should be deleted once the next release comes out.
     # TODO: It fixes a bug that prevented us from linking to Tk/Tcl.
@@ -65,7 +66,8 @@ class PyPillow(Package):
 
     # Required dependencies
     extends('python')
-    depends_on('binutils', type='build')
+    # Known not to work with 2.23, 2.25
+    depends_on('binutils@2.26:', type='build')
     depends_on('py-setuptools', type='build')
 
     # Recommended dependencies

var/spack/repos/builtin/packages/py-scipy/package.py

@@ -36,6 +36,7 @@ class PyScipy(Package):
 
     extends('python')
     depends_on('py-nose', type='build')
+    depends_on('binutils@2.26:', type='build')
     depends_on('py-numpy+blas+lapack', type=nolink)
 
     def install(self, spec, prefix):