cleanup: avoid _ for local unused tmp variables - that is reserved for i18n

cleanup: avoid _ for local unused tmp variables - that is reserved for i18n

_ is usually used for i18n markup but we also used it for I-don't-care
variables.

Instead, name don't-care variables in a slightly descriptive way but use the _
prefix to designate unused variable.

This will mute some pyflakes "import '_' ... shadowed by loop variable"
warnings.

--- a/hgext/shelve.py	Fri Aug 15 04:37:45 2014 +0200
+++ b/hgext/shelve.py	Fri Aug 15 16:20:47 2014 +0200
@@ -269,7 +269,7 @@
     wlock = None
     try:
         wlock = repo.wlock()
-        for (name, _) in repo.vfs.readdir('shelved'):
+        for (name, _type) in repo.vfs.readdir('shelved'):
             suffix = name.rsplit('.', 1)[-1]
             if suffix in ('hg', 'files', 'patch'):
                 shelvedfile(repo, name).unlink()
@@ -303,7 +303,7 @@
             raise
         return []
     info = []
-    for (name, _) in names:
+    for (name, _type) in names:
         pfx, sfx = name.rsplit('.', 1)
         if not pfx or sfx != 'patch':
             continue

--- a/mercurial/hgweb/webcommands.py	Fri Aug 15 04:37:45 2014 +0200
+++ b/mercurial/hgweb/webcommands.py	Fri Aug 15 16:20:47 2014 +0200
@@ -1069,7 +1069,7 @@
     topicname = req.form.get('node', [None])[0]
     if not topicname:
         def topics(**map):
-            for entries, summary, _ in helpmod.helptable:
+            for entries, summary, _doc in helpmod.helptable:
                 yield {'topic': entries[0], 'summary': summary}
 
         early, other = [], []

--- a/mercurial/transaction.py	Fri Aug 15 04:37:45 2014 +0200
+++ b/mercurial/transaction.py	Fri Aug 15 16:20:47 2014 +0200
@@ -115,10 +115,10 @@
 
         offsets = []
         backups = []
-        for f, o, _ in q[0]:
+        for f, o, _data in q[0]:
             offsets.append((f, o))
 
-        for f, b, _ in q[1]:
+        for f, b, _data in q[1]:
             backups.append((f, b))
 
         d = ''.join(['%s\0%d\n' % (f, o) for f, o in offsets])
@@ -265,7 +265,7 @@
             self.opener.unlink(self.journal)
         if self.opener.isfile(self.backupjournal):
             self.opener.unlink(self.backupjournal)
-            for f, b, _ in self.backupentries:
+            for f, b, _ignore in self.backupentries:
                 self.opener.unlink(b)
         self.backupentries = []
         self.journal = None

--- a/mercurial/worker.py	Fri Aug 15 04:37:45 2014 +0200
+++ b/mercurial/worker.py	Fri Aug 15 16:20:47 2014 +0200
@@ -105,7 +105,7 @@
                 if err.errno != errno.ESRCH:
                     raise
     def waitforworkers():
-        for _ in pids:
+        for _pid in pids:
             st = _exitstatus(os.wait()[1])
             if st and not problem[0]:
                 problem[0] = st