--- configure.ac	2015/06/08 02:27:18	1.1
+++ configure.ac	2015/06/08 20:59:12
@@ -1153,43 +1153,47 @@
 		AC_MSG_RESULT($CC)
 	    fi
 
-	    # Calculate the right deployment target for this build.
-	    #
-		cur_target_major=`sw_vers -productVersion | \
-				sed 's/\([[0-9]]*\)\.\([[0-9]]*\).*/\1/'`
-		cur_target_minor=`sw_vers -productVersion | \
-				sed 's/\([[0-9]]*\)\.\([[0-9]]*\).*/\2/'`
-		cur_target="${cur_target_major}.${cur_target_minor}"
-		if test ${cur_target_major} -eq 10 && \
-		   test ${cur_target_minor} -ge 3
-		then
-		    cur_target=10.3
-		    if test ${enable_universalsdk}; then
-			    if test "${UNIVERSAL_ARCHS}" = "all"; then
-				    # Ensure that the default platform for a 
-				    # 4-way universal build is OSX 10.5, 
-				    # that's the first OS release where 
-				    # 4-way builds make sense.
-				    cur_target='10.5'
-
-			    elif test "${UNIVERSAL_ARCHS}" = "3-way"; then
-				    cur_target='10.5'
-
-			    elif test "${UNIVERSAL_ARCHS}" = "intel"; then
-				    cur_target='10.5'
-
-			    elif test "${UNIVERSAL_ARCHS}" = "64-bit"; then
-				    cur_target='10.5'
-			    fi
-		    else
-			    if test `/usr/bin/arch` = "i386"; then
-				    # On Intel macs default to a deployment
-				    # target of 10.4, that's the first OSX
-				    # release with Intel support.
-				    cur_target="10.4"
-			    fi
-		    fi
-	    fi
+        # Calculate an appropriate deployment target for this build:
+        # The deployment target value is used explicitly to enable certain
+        # features are enabled (such as builtin libedit support for readline)
+        # through the use of Apple's Availabiliy Macros and is used as a
+        # component of the string returned by distutils.get_platform().
+        #
+        # Use the value from:
+        # 1. the MACOSX_DEPLOYMENT_TARGET environment variable if specified
+        # 2. the operating system version of the build machine if >= 10.6
+        # 3. If running on OS X 10.3 through 10.5, use the legacy tests
+        #       below to pick either 10.3, 10.4, or 10.5 as the target.
+        # 4. If we are running on OS X 10.2 or earlier, good luck!
+
+        AC_MSG_CHECKING(which MACOSX_DEPLOYMENT_TARGET to use)
+        cur_target_major=`sw_vers -productVersion | \
+                sed 's/\([[0-9]]*\)\.\([[0-9]]*\).*/\1/'`
+        cur_target_minor=`sw_vers -productVersion | \
+                sed 's/\([[0-9]]*\)\.\([[0-9]]*\).*/\2/'`
+        cur_target="${cur_target_major}.${cur_target_minor}"
+        if test ${cur_target_major} -eq 10 && \
+           test ${cur_target_minor} -ge 3 && \
+           test ${cur_target_minor} -le 5
+        then
+            # OS X 10.3 through 10.5
+            cur_target=10.3
+            if test ${enable_universalsdk}
+            then
+                case "$UNIVERSAL_ARCHS" in
+                all|3-way|intel|64-bit)
+                    # These configurations were first supported in 10.5
+                    cur_target='10.5'
+                    ;;
+                esac
+            else
+                if test `/usr/bin/arch` = "i386"
+                then
+                    # 10.4 was the first release to support Intel archs
+                    cur_target="10.4"
+                fi
+            fi
+        fi
 	    CONFIGURE_MACOSX_DEPLOYMENT_TARGET=${MACOSX_DEPLOYMENT_TARGET-${cur_target}}
 	    
 	    # Make sure that MACOSX_DEPLOYMENT_TARGET is set in the 
@@ -1199,6 +1203,7 @@
 	    MACOSX_DEPLOYMENT_TARGET="$CONFIGURE_MACOSX_DEPLOYMENT_TARGET"
 	    export MACOSX_DEPLOYMENT_TARGET
 	    EXPORT_MACOSX_DEPLOYMENT_TARGET=''
+	    AC_MSG_RESULT($MACOSX_DEPLOYMENT_TARGET)
 
 	    if test "${enable_universalsdk}"; then
 		UNIVERSAL_ARCH_FLAGS=""