Fixed writing graphs to relative paths (#3378)

While playing around with the 'import-graph' setting, I noticed that attempting to write a graph to a local directory did not work as I would have expected.
For example, 'import-graph=docs/graph.dot' would attempt to add 'graph.dot' to '/LOCAL/PATH/docs/docs/'.
This was because the 'dot_sourcepath' in this scenario would be set to the combination of the 'storedir' ('/LOCAL/PATH/docs') and the 'outputfile' ('docs/graph.dot'). I am requesting that it be changed to just be 'outputfile' in this scenario.

Also, I have removed the instantiation of the 'dotfile' variable because it now has no use

Co-authored-by: Claudiu Popa <pcmanticore@gmail.com>

3 files changed, 7 insertions, 13 deletions

diff --git a/CONTRIBUTORS.txt b/CONTRIBUTORS.txt
index eb96651a5..0b82832b7 100644
--- a/CONTRIBUTORS.txt
+++ b/CONTRIBUTORS.txt
@@ -366,4 +366,7 @@ contributors:
 
 * Anubhav: contributor
 
+* Ben Graham: contributor
+
 * Anthony Tan: contributor
+
diff --git a/ChangeLog b/ChangeLog
index 85a37b566..6a637e4d8 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -7,9 +7,7 @@ What's New in Pylint 2.5.0?
 
 Release date: TBA
 
-* Remove unused import 
-  
-  Close #3379
+* Fixed graph creation for relative paths
 
 * Add a check for asserts on string literals.
 
diff --git a/pylint/graph.py b/pylint/graph.py
index 0dc7a1460..9e0348144 100644
--- a/pylint/graph.py
+++ b/pylint/graph.py
@@ -71,30 +71,23 @@ class DotBackend:
 
     source = property(get_source)
 
-    def generate(self, outputfile=None, dotfile=None, mapfile=None):
+    def generate(self, outputfile=None, mapfile=None):
         """Generates a graph file.
 
         :param str outputfile: filename and path [defaults to graphname.png]
-        :param str dotfile: filename and path [defaults to graphname.dot]
         :param str mapfile: filename and path
 
         :rtype: str
         :return: a path to the generated file
         """
         name = self.graphname
-        if not dotfile:
-            # if 'outputfile' is a dot file use it as 'dotfile'
-            if outputfile and outputfile.endswith(".dot"):
-                dotfile = outputfile
-            else:
-                dotfile = "%s.dot" % name
         if outputfile is not None:
-            storedir, _, target = target_info_from_filename(outputfile)
+            _, _, target = target_info_from_filename(outputfile)
             if target != "dot":
                 pdot, dot_sourcepath = tempfile.mkstemp(".dot", name)
                 os.close(pdot)
             else:
-                dot_sourcepath = osp.join(storedir, dotfile)
+                dot_sourcepath = outputfile
         else:
             target = "png"
             pdot, dot_sourcepath = tempfile.mkstemp(".dot", name)