Refuse branch/tag names that start with a dot

In git, branch and tag names are not allowed to start with a dot.

In bup, we also want to enforce this since we want to avoid collision with the
top-level special directories (.commit and .tag).

Also, in save-cmd, there was an unused variable at line 286. 'oldref' is used
and contains the same thing so get rid of 'ref'.

Signed-off-by: Gabriel Filion <lelutin@gmail.com>

cmd/save-cmd.py

@@ -40,6 +40,8 @@
 if is_reverse and opt.remote:
     o.fatal("don't use -r in reverse mode; it's automatic")
 
+if opt.name and opt.name.startswith('.'):
+    o.fatal("'%s' is not a valid branch name" % opt.name)
 refname = opt.name and 'refs/heads/%s' % opt.name or None
 if opt.remote or is_reverse:
     cli = client.Client(opt.remote)
@@ -283,7 +285,6 @@ def wantrecurse_during(ent):
     print tree.encode('hex')
 if opt.commit or opt.name:
     msg = 'bup save\n\nGenerated by command:\n%r' % sys.argv
-    ref = opt.name and ('refs/heads/%s' % opt.name) or None
     commit = w.new_commit(oldref, tree, date, msg)
     if opt.commit:
         print commit.encode('hex')

cmd/split-cmd.py

@@ -78,6 +78,8 @@ def prog(filenum, nbytes):
     o.fatal("don't use -r in reverse mode; it's automatic")
 start_time = time.time()
 
+if opt.name and opt.name.startswith('.'):
+    o.fatal("'%s' is not a valid branch name." % opt.name)
 refname = opt.name and 'refs/heads/%s' % opt.name or None
 if opt.noop or opt.copy:
     cli = pack_writer = oldref = None

cmd/tag-cmd.py

@@ -58,6 +58,9 @@
     log("bup: error: tag '%s' already exists" % tag_name)
     sys.exit(1)
 
+if tag_name.startswith('.'):
+    o.fatal("'%s' is not a valid tag name." % tag_name)
+
 try:
     hash = git.rev_parse(commit)
 except git.GitError, e: