Rewrite contributor lister in Python.

RELEASE.txt

@@ -5,7 +5,7 @@ How to make a new release of ``skimage``
 
 - Update release notes.
 
-  - To show a list contributors, run ``doc/release/contributors.sh <commit>``,
+  - To show a list contributors, run ``doc/release/contributors.py <commit>``,
     where ``<commit>`` is the first commit since the previous release.
 
 - Update the version number in ``setup.py`` and ``bento.info`` and commit

doc/release/contributors.py

@@ -0,0 +1,23 @@
+#!/usr/bin/env python
+import subprocess
+import sys
+import string
+
+if len(sys.argv) != 2:
+    print "Usage: ./contributors.py tag-of-previous-release"
+    sys.exit(-1)
+
+tag = sys.argv[1]
+
+cmd = "git log %s..HEAD --format=%%aN"
+authors = subprocess.check_output((cmd % tag).split()).split('\n')
+authors = [a.strip() for a in authors if a.strip()]
+
+def key(author):
+    author = [v for v in author.split() if v[0] in string.letters]
+    return author[-1]
+
+authors = sorted(set(authors), key=key)
+
+for a in authors:
+    print '-', a

doc/release/contributors.sh

@@ -1,2 +0,0 @@
-git log $1..HEAD --format='- %aN' | sed 's/@/\-at\-/' | sed 's/<>//' | sort -u
-