churn: do not crash on empty lines in alias file

hgext/churn.py

@@ -129,6 +129,8 b' def churn(ui, repo, *pats, **opts):'
         aliases = repo.wjoin('.hgchurn')
     if aliases:
         for l in open(aliases, "r"):
+            if not l.strip():
+                continue
             alias, actual = l.split('=' in l and '=' or None, 1)
             amap[alias.strip()] = actual.strip()
 

tests/test-churn

@@ -38,6 +38,7 b' cd ..'
 echo % churn with aliases
 cat > ../aliases <<EOF
 user1 alias1
+
 user3 alias3
 EOF
 hg churn --aliases ../aliases