Merge pull request #710 from thopiekar/pythonpath-fix-reworked

[master] PYTHONPATH fix reworked

cura_app.py

@@ -3,8 +3,25 @@
 # Copyright (c) 2015 Ultimaker B.V.
 # Cura is released under the terms of the AGPLv3 or higher.
 
+import os
 import sys
 
+#WORKAROUND: GITHUB-704 GITHUB-708
+# It looks like setuptools creates a .pth file in
+# the default /usr/lib which causes the default site-packages
+# to be inserted into sys.path before PYTHONPATH.
+# This can cause issues such as having libsip loaded from
+# the system instead of the one provided with Cura, which causes
+# incompatibility issues with libArcus
+if "PYTHONPATH" in os.environ.keys():                       # If PYTHONPATH is used
+    PYTHONPATH = os.environ["PYTHONPATH"].split(os.pathsep) # Get the value, split it..
+    PYTHONPATH.reverse()                                    # and reverse it, because we always insert at 1
+    for PATH in PYTHONPATH:                                 # Now beginning with the last PATH
+        PATH_real = os.path.realpath(PATH)                  # Making the the path "real"
+        if PATH_real in sys.path:                           # This should always work, but keep it to be sure..
+            sys.path.remove(PATH_real)
+        sys.path.insert(1, PATH_real)                       # Insert it at 1 after os.curdir, which is 0.
+
 def exceptHook(hook_type, value, traceback):
     import cura.CrashHandler
     cura.CrashHandler.show(hook_type, value, traceback)