mapping Tabular plugin not working for '{'

[neilhwatson]

Consider this map:

nnoremap <leader>a :Tabularize<CR>

And this sample text:

fe =>
feoefij =>
feon =>

fe =
feoefij =
feon =

fe {
feoefij {
feon {

When I put the cursor on any block and a Tabular aligns the = and the =>, but not {. Strangely if, on the last block, in normal mode I :Tabularize the { are aligned. Why did the map fail?

Using vim-tabular/stable,now 1.0-3 all in Debian.