Ignore IOErrors when checking for already installed files

core/helpers.py

@@ -42,21 +42,30 @@ def get_text_files(directory):
 def detect_installed_file(current_file, test_files):
     """Returns the file in <test_files> which is contained in
     <current_file>, or "Unknown"."""
-    current = open(current_file).read()
-    for f in test_files:
-        tested = open(f).read()
-        if tested in current:
-            return f
+    try:
+        current = open(current_file).read()
+        for f in test_files:
+            tested = open(f).read()
+            if tested in current:
+                return f
+    except IOError:
+        pass
     return "Unknown"
 
 def detect_installed_files(current_file, test_files):
     """Returns a list of files in <test_files> that are contained in
     <current_file>."""
-    current = open(current_file).read()
     installed = []
-    for f in test_files:
-        tested = open(f).read()
-        if tested in current:
-            installed.append(f)
+    try:
+        current = open(current_file).read()
+        for f in test_files:
+            try:
+                tested = open(f).read()
+                if tested in current:
+                    installed.append(f)
+            except IOError:
+                pass
+    except IOError:
+        pass
     return installed