write_tree: suppress double-slash in blob HTML filename
write_tree: suppress double-slash in blob HTML filename

When emitting a blob in the root tree of a commit, write_tree() composes
the blob's HTML filename with an extra slash before the "f=", like this:

    output/r/repo/b/master/t//f=README.txt.html

Although the double-slash is not harmful on Unix, it is unsightly, and
may be problematic for other platforms or filesystems which interpret
double-slash specially or disallow it. Therefore, suppress the extra
slash for blobs in the root tree.

Signed-off-by: Eric Sunshine <8d6e34f987851aa599257d3831a1af040886842f@sunshineco.com>
Signed-off-by: Alberto Bertogli <aa51a345a0e8173877757331a6c3833d48834cb6@blitiri.com.ar>

oz123/git-arr,oz123/git-arr,oz123/git-arr