Fix dep-graph command: outdated import

The `--dep-graph` command uses `graphviz-python` (`import gv`) to convert a dot-graph into an image file. This library seems outdated. In pip it is now called `graphviz` and the API is slightly different. The docs already refer to it.
This commit fixes the import and the function that renders the graph image.

Author: lorisercole

easybuild/framework/easyconfig/tools.py

@@ -80,14 +80,7 @@
     # https://pypi.python.org/pypi/python-graph-dot
     import pygraph.readwrite.dot as dot
     # graphviz (used for creating dependency graph images)
-    sys.path.append('..')
-    sys.path.append('/usr/lib/graphviz/python/')
-    sys.path.append('/usr/lib64/graphviz/python/')
-    # Python bindings to Graphviz (http://www.graphviz.org/),
-    # see https://pypi.python.org/pypi/graphviz-python
-    # graphviz-python (yum) or python-pygraphviz (apt-get)
-    # or brew install graphviz --with-bindings (OS X)
-    import gv
+    import graphviz
 except ImportError:
     pass
 
@@ -244,13 +237,14 @@ def _dep_graph_dump(dgr, filename):
         return _dep_graph_gv(dottxt, filename)
 
 
-@only_if_module_is_available('gv', pkgname='graphviz-python')
+@only_if_module_is_available('graphviz', pkgname='graphviz')
 def _dep_graph_gv(dottxt, filename):
     """Render dependency graph to file using graphviz."""
     # try and render graph in specified file format
-    gvv = gv.readstring(dottxt)
-    if gv.layout(gvv, 'dot') is not False:
-        return gv.render(gvv, os.path.splitext(filename)[-1], filename)
+    gvv = graphviz.Source(dottxt)
+    if gvv.pipe():
+        name, ext = os.path.splitext(filename)
+        return gvv.render(filename=name, format=ext[1:], cleanup=True)
 
 
 def get_paths_for(subdir=EASYCONFIGS_PKG_SUBDIR, robot_path=None):

easybuild/tools/systemtools.py

@@ -202,7 +202,7 @@
     'autopep8': (None, "auto-formatting for dumped easyconfigs"),
     'GC3Pie': ('gc3libs', "backend for --job"),
     'GitPython': ('git', "GitHub integration + using Git repository as easyconfigs archive"),
-    'graphviz-python': ('gv', "rendering dependency graph with Graphviz: --dep-graph"),
+    'graphviz': ('graphviz', "rendering dependency graph with Graphviz: --dep-graph"),
     'keyring': (None, "storing GitHub token"),
     'pbs-python': ('pbs', "using Torque as --job backend"),
     'pycodestyle': (None, "code style checking: --check-style, --check-contrib"),