Problems updating gcc git mirror clone

[Andrey Gursky <andrey dot gursky at e-mail dot ua>]

Dear list members,

On March 4 it was the last time I was able successfully to update my
local clone of gcc git mirror, which has been setup as described in
[1].

$ git pull --rebase
>From git://gcc.gnu.org/git/gcc
   7628458..79bac32  trunk      -> svn/trunk
   f379260..0417bef  gcc-4_8-branch -> origin/gcc-4_8-branch
   42a9765..b0ec7b6  gcc-4_9-branch -> origin/gcc-4_9-branch
   7628458..79bac32  master     -> origin/master
   7628458..79bac32  trunk      -> origin/trunk
   4e11d32..69d7068  ARM        -> svn/ARM
   b3d2c22..16d26e1  c++-delayed-folding -> svn/c++-delayed-folding
   f379260..0417bef  gcc-4_8-branch -> svn/gcc-4_8-branch
   42a9765..b0ec7b6  gcc-4_9-branch -> svn/gcc-4_9-branch
   101f03f..2d017af  google     -> svn/google
   7ec246e..689171f  gupc       -> svn/gupc
   9d2feef..6a9948a  ibm        -> svn/ibm
   d5bea86..ee7a90e  redhat     -> svn/redhat
 * [new ref]         ttype3     -> svn/ttype3
First, rewinding head to replay your work on top of it...
Fast-forwarded trunk to 79bac32ec3283a9a73faeec11b8d905e4cf1445a.
$

The next time I did update on March 7 and it failed:

$ git pull --rebase
>From git://gcc.gnu.org/git/gcc
   79bac32..74eacc0  trunk      -> svn/trunk
   0417bef..5adbe99  gcc-4_8-branch -> origin/gcc-4_8-branch
   b0ec7b6..e510458  gcc-4_9-branch -> origin/gcc-4_9-branch
error: 'refs/remotes/origin/hjl/pie' exists; cannot create
'refs/remotes/origin/hjl/pie/gcc-4_9-branch'
 ! [new branch]      hjl/pie/gcc-4_9-branch ->
origin/hjl/pie/gcc-4_9-branch  (unable to update local ref)
error: 'refs/remotes/origin/hjl/pie' exists; cannot create
'refs/remotes/origin/hjl/pie/master'
 ! [new branch]      hjl/pie/master -> origin/hjl/pie/master  (unable
to update local ref)
 * [new branch]      hjl/pr65248 -> origin/hjl/pr65248
   79bac32..74eacc0  master     -> origin/master
   79bac32..74eacc0  trunk      -> origin/trunk
   0417bef..5adbe99  gcc-4_8-branch -> svn/gcc-4_8-branch
   b0ec7b6..e510458  gcc-4_9-branch -> svn/gcc-4_9-branch
   fe83068..b315806  linaro     -> svn/linaro
error: some local refs could not be updated; try running
 'git remote prune origin' to remove any old, conflicting branches
$

Is it a "normal" behavior for git clone of a svn repository or it's
something wrong?

[1] https://gcc.gnu.org/wiki/GitMirror#Getting_started_-_Read-Only

Thanks,
Andrey