shortuser should stop before the first space character.

Examples:
"Foo Bar <foo.bar AT example DOT com>" -> "foo.bar"
(instead of "foo.bar AT example DOT com>" as it was before.)
"Foo Bar" -> "Foo"

mercurial/util.py

@@ -948,6 +948,9 b' def shortuser(user):'
     f = user.find('<')
     if f >= 0:
         user = user[f+1:]
+    f = user.find(' ')
+    if f >= 0:
+        user = user[:f]
     return user
 
 def walkrepos(path):