return ENOTSUP when branches empty after update

src/branches.cpp

@@ -205,6 +205,9 @@ namespace l
     Branches::Impl tmp_branches(branches_->minfreespace());
 
     str::split(str_,':',&paths);
+    if (paths.empty())
+      return -ENOTSUP;
+
     for(auto &path : paths)
       {
         rv = l::parse(path,&tmp_branches);
@@ -269,6 +272,9 @@ namespace l
   int
   erase_begin(Branches::Impl *branches_)
   {
+    if (branches_->size() <= 1)
+      return -ENOTSUP;
+
     branches_->erase(branches_->begin());
 
     return 0;
@@ -278,6 +284,9 @@ namespace l
   int
   erase_end(Branches::Impl *branches_)
   {
+    if (branches_->size() <= 1)
+      return -ENOTSUP;
+
     branches_->pop_back();
 
     return 0;
@@ -299,6 +308,8 @@ namespace l
           {
             match = ::fnmatch(pi->c_str(),i->path.c_str(),0);
           }
+        if (match == 0 && branches_->size() == 1)
+          return -ENOTSUP;
 
         i = ((match == 0) ? branches_->erase(i) : (i+1));
       }