Add script to convert formulae from MD5 to SHA1.

Library/Contributions/cmds/brew-md5-to-sha1

@@ -0,0 +1,24 @@
+#!/bin/sh
+# Change every formula's MD5 to a SHA1.
+
+HOMEBREW_PREFIX=$(brew --config | grep HOMEBREW_PREFIX | sed -e 's/HOMEBREW_PREFIX: //')
+cd $HOMEBREW_PREFIX/Library/Formula
+FORMULAE=$(grep "^  md5 " -rl . | sed -e 's/\.\///' -e 's/\.rb$//')
+
+for FORMULA in $FORMULAE
+do
+	echo "Fetching and SHA1ing $FORMULA"
+	if brew fetch $FORMULA &>/dev/null
+	then
+		SHA1=$(brew fetch $FORMULA | grep SHA1 | sed -e 's/SHA1: //')
+		sed -i.old -e "s/^  md5 *[\"'][a-fA-F0-9]\{32\}[\"']/  sha1 '$SHA1'/" $FORMULA.rb
+		rm $FORMULA.rb.old
+		if !brew fetch $FORMULA &>/dev/null
+		then
+			echo "Error: SHA1ing $FORMULA failed, reverting"
+			git checkout $FORMULA.rb
+		fi
+	else
+		echo "Error: fetching $FORMULA failed, skipping"
+	fi
+done