This reverts r63675 based on the discussion in this thread:

 http://mail.python.org/pipermail/python-dev/2008-June/079988.html

Python 2.6 should stick with PyString_* in its codebase.  The PyBytes_* names
in the spirit of 3.0 are available via a #define only.  See the email thread.
diff --git a/Modules/imgfile.c b/Modules/imgfile.c
index 5a8adf2..baa6ead 100644
--- a/Modules/imgfile.c
+++ b/Modules/imgfile.c
@@ -130,12 +130,12 @@
 	}
 
 	if ( zsize == 3 ) zsize = 4;
-	rv = PyBytes_FromStringAndSize((char *)NULL, xsize*ysize*zsize);
+	rv = PyString_FromStringAndSize((char *)NULL, xsize*ysize*zsize);
 	if ( rv == NULL ) {
 		iclose(image);
 		return NULL;
 	}
-	cdatap = PyBytes_AsString(rv);
+	cdatap = PyString_AsString(rv);
 	idatap = (long *)cdatap;
 
 	if (top_to_bottom) {
@@ -319,7 +319,7 @@
 	}
 
 	if ( zsize == 3 ) zsize = 4;
-	rv = PyBytes_FromStringAndSize(NULL, xwtd*ywtd*zsize);
+	rv = PyString_FromStringAndSize(NULL, xwtd*ywtd*zsize);
 	if ( rv == NULL ) {
 		iclose(image);
 		return NULL;
@@ -328,7 +328,7 @@
 	xfac = (float)xsize/(float)xwtd;
 	yfac = (float)ysize/(float)ywtd;
 	PyFPE_END_PROTECT(yfac)
-	cdatap = PyBytes_AsString(rv);
+	cdatap = PyString_AsString(rv);
 	idatap = (long *)cdatap;
 
 	if ( extended ) {