patch 7.4.1012

Problem:    Vim overwrites the value of $PYTHONHOME.
Solution:   Do not set $PYTHONHOME if it is already set. (Kazuki Sakamoto,
            closes #500)

src/if_python.c

@@ -928,7 +928,10 @@ Python_Init(void)
 #endif
 
 #ifdef PYTHON_HOME
-	Py_SetPythonHome(PYTHON_HOME);
+# ifdef DYNAMIC_PYTHON
+	if (mch_getenv((char_u *)"PYTHONHOME") == NULL)
+# endif
+	    Py_SetPythonHome(PYTHON_HOME);
 #endif
 
 	init_structs();

src/if_python3.c

@@ -858,7 +858,10 @@ Python3_Init(void)
 
 
 #ifdef PYTHON3_HOME
-	Py_SetPythonHome(PYTHON3_HOME);
+# ifdef DYNAMIC_PYTHON3
+	if (mch_getenv((char_u *)"PYTHONHOME") == NULL)
+# endif
+	    Py_SetPythonHome(PYTHON3_HOME);
 #endif
 
 	PyImport_AppendInittab("vim", Py3Init_vim);

src/version.c

@@ -741,6 +741,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1012,
 /**/
     1011,
 /**/