I had the same issue. When I checked my config file I noticed that 'fetch = +refs/heads/:refs/remotes/origin/' was on the same line as 'url = Z:/GIT/REPOS/SEL.git' as shown:
[core]
repositoryformatversion = 0
filemode = false
bare = false
logallrefupdates = true
symlinks = false
ignorecase = true
[remote "origin"]
url = Z:/GIT/REPOS/SEL.git fetch = +refs/heads/*:refs/remotes/origin/*
[branch "master"]
remote = origin
merge = refs/heads/master
[gui]
wmstate = normal
geometry = 1109x563+32+32 216 255
At first I did not think that this would have mattered but after seeing the post by Magere I moved the line and that fixed the problem:
[core]
repositoryformatversion = 0
filemode = false
bare = false
logallrefupdates = true
symlinks = false
ignorecase = true
[remote "origin"]
url = Z:/GIT/REPOS/SEL.git
fetch = +refs/heads/*:refs/remotes/origin/*
[branch "master"]
remote = origin
merge = refs/heads/master
[gui]
wmstate = normal
geometry = 1109x563+32+32 216 255