Fix a possible error on some combinations of markers

CHANGELOG.md

 # Change Log
 
+## [Unreleased]
+
+### Fixed
+
+- Fixed possible error on some combinations of markers.
+
+
 ## [0.12.3] - 2018-10-18
 
 ### Fixed

poetry/packages/utils/utils.py

@@ -139,22 +139,27 @@ def convert_markers(marker):
     requirements = {}
 
     def _group(_groups, or_=False):
+        ors = {}
         for group in _groups:
-            if isinstance(group, tuple):
+            if isinstance(group, list):
+                _group(group, or_=True)
+            else:
                 variable, op, value = group
                 group_name = str(variable)
                 if group_name not in requirements:
-                    requirements[group_name] = [[]]
-                elif or_:
-                    requirements[group_name].append([])
+                    requirements[group_name] = []
+
+                if group_name not in ors:
+                    ors[group_name] = or_
 
-                or_ = False
+                if ors[group_name] or not requirements[group_name]:
+                    requirements[group_name].append([])
 
                 requirements[group_name][-1].append((str(op), str(value)))
-            else:
-                _group(group, or_=True)
 
-    _group(groups)
+                ors[group_name] = False
+
+    _group(groups, or_=True)
 
     return requirements
 

tests/packages/utils/test_utils.py

+from poetry.packages.utils.utils import convert_markers
+from poetry.version.markers import parse_marker
+
+
+def test_convert_markers():
+    marker = parse_marker(
+        'sys_platform == "win32" and python_version < "3.6" '
+        'or sys_platform == "win32" and python_version < "3.6" and python_version >= "3.3" '
+        'or sys_platform == "win32" and python_version < "3.3"'
+    )
+
+    converted = convert_markers(marker)
+
+    assert converted["python_version"] == [
+        [("<", "3.6")],
+        [("<", "3.6"), (">=", "3.3")],
+        [("<", "3.3")],
+    ]
+
+    marker = parse_marker('python_version == "2.7" or python_version == "2.6"')
+    converted = convert_markers(marker)
+
+    assert converted["python_version"] == [[("==", "2.7")], [("==", "2.6")]]