Index: Lib/site.py
===================================================================
--- Lib/site.py	(revision 87478)
+++ Lib/site.py	(working copy)
@@ -55,6 +55,7 @@
 import sys
 import os
 import builtins
+import traceback
 
 # Prefixes for site-packages; add additional prefixes like /usr/local here
 PREFIXES = [sys.prefix, sys.exec_prefix]
@@ -141,17 +142,26 @@
     except IOError:
         return
     with f:
-        for line in f:
+        for n, line in enumerate(f):
             if line.startswith("#"):
                 continue
-            if line.startswith(("import ", "import\t")):
-                exec(line)
-                continue
-            line = line.rstrip()
-            dir, dircase = makepath(sitedir, line)
-            if not dircase in known_paths and os.path.exists(dir):
-                sys.path.append(dir)
-                known_paths.add(dircase)
+            try:
+                if line.startswith(("import ", "import\t")):
+                    exec(line)
+                    continue
+                line = line.rstrip()
+                dir, dircase = makepath(sitedir, line)
+                if not dircase in known_paths and os.path.exists(dir):
+                    sys.path.append(dir)
+                    known_paths.add(dircase)
+            except Exception as err:
+                print("Error processing line {:d} of {}:\n".format(n+1, fullname),
+                      file=sys.stderr)
+                for record in traceback.format_exception(*sys.exc_info()):
+                    for line in record.splitlines():
+                        print('  '+line, file=sys.stderr)
+                print("\nRemainder of file ignored")
+                break
     if reset:
         known_paths = None
     return known_paths
@@ -174,7 +184,13 @@
         return
     names = [name for name in names if name.endswith(".pth")]
     for name in sorted(names):
-        addpackage(sitedir, name, known_paths)
+        try:
+            addpackage(sitedir, name, known_paths)
+        except Exception as err:
+            print("Error processing %r:\n" % os.path.join(sitedir, name),
+                  file=sys.stderr)
+            traceback.print_exc(file=sys.stderr)
+            continue
     if reset:
         known_paths = None
     return known_paths