A few bugfixes:

theano/configdefaults.py

@@ -74,9 +74,13 @@ AddConfigVar('mode',
                 'FAST_COMPILE', 'PROFILE_MODE', 'DEBUG_MODE'),
         in_c_key=False)
 
-# Test whether or not gcc is present: disable C code if it is not
+# Test whether or not gcc is present: disable C code if it is not.
+# Using the dummy file descriptor below is a workaround for a crash experienced
+# in an unusual Python 2.4.4 Windows environment with the default stdin=None.
+dummy_stdin = open(os.devnull)
 try:
-    subprocess.Popen('gcc', stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+    subprocess.Popen('gcc', stdout=subprocess.PIPE, stderr=subprocess.PIPE,
+                     stdin=dummy_stdin.fileno())
     # Keep the default linker the same as the one for the mode FAST_RUN
     AddConfigVar('linker',
                  "Default linker used if the theano flags mode is Mode or ProfileMode",
@@ -92,6 +96,8 @@ except OSError:
             'C-implementations (for both CPU and GPU) and will default to '+
             'Python implementations. Performance will be severely degraded.')
 
+del dummy_stdin
+
 #Keep the default optimizer the same as the one for the mode FAST_RUN
 AddConfigVar('optimizer',
         "Default optimizer. If not None, will use this linker with the Mode object(not ProfileMode or DebugMode)",

theano/gof/cmodule.py

@@ -224,7 +224,7 @@ def is_same_entry(entry_1, entry_2):
 
     This is the case if and only if at least one of these conditions holds:
         - They are equal.
-        - There real paths are equal.
+        - Their real paths are equal.
         - They share the same temporary work directory and module file name.
     """
     if entry_1 == entry_2:
@@ -234,7 +234,7 @@ def is_same_entry(entry_1, entry_2):
     if (os.path.basename(entry_1) == os.path.basename(entry_2) and
         (os.path.basename(os.path.dirname(entry_1)) ==
          os.path.basename(os.path.dirname(entry_2))) and
-        os.path.basename(os.path.dirname(entry_1).startswith('tmp'))):
+        os.path.basename(os.path.dirname(entry_1)).startswith('tmp')):
         return True
     return False
 
@@ -594,8 +594,12 @@ class ModuleCache(object):
                         kd_entry = key_data.get_entry()
                         if kd_entry != entry:
                             if is_same_entry(entry, kd_entry):
-                                # Update KeyData object.
+                                # Update KeyData object. Note that we also need
+                                # to update the key_pkl field, because it is
+                                # likely to be incorrect if the entry itself
+                                # was wrong.
                                 key_data.entry = entry
+                                key_data.key_pkl = key_pkl
                             else:
                                 # This is suspicious. Better get rid of it.
                                 _rmtree(root, ignore_nocleanup=True,
@@ -1248,10 +1252,22 @@ def std_libs():
 def std_lib_dirs():
     return std_lib_dirs_and_libs()[1]
 
-p=subprocess.Popen(['gcc','-dumpversion'],stdout=subprocess.PIPE)
-p.wait()
-gcc_version_str = p.stdout.readline().strip()
+# Using the dummy file descriptors below is a workaround for a crash experienced
+# in an unusual Python 2.4.4 Windows environment with the default None values.
+dummy_in = open(os.devnull)
+dummy_err = open(os.devnull, 'w')
+p = None
+try:
+    p = subprocess.Popen(['gcc', '-dumpversion'], stdout=subprocess.PIPE,
+                         stdin=dummy_in.fileno(), stderr=dummy_err.fileno())
+    p.wait()
+    gcc_version_str = p.stdout.readline().strip()
+except OSError:
+    # Typically means gcc cannot be found.
+    gcc_version_str = 'GCC_NOT_FOUND'
 del p
+del dummy_in
+del dummy_err
 
 def gcc_version():
     return gcc_version_str