Errors reading/writing while downloading

[jfontan]

They point to the same file:

time="2019-06-13T16:53:16.698967058+02:00" level=error msg=failed error="index read failed: seek /home/jfontan/work/gitcollector/sivas-new/f2/f281ab6f2e0e38dcc3af05360667d8f530c00103.siva: invalid argument" id=41441ce5-149a-4df6-be0e-3ea5c187eac4 job=download source="downloader/download.go:61" url="https://github.com/src-d/core-retrieval"
time="2019-06-13T16:53:16.702707441+02:00" level=error msg=failed error="index read failed: seek /home/jfontan/work/gitcollector/sivas-new/f2/f281ab6f2e0e38dcc3af05360667d8f530c00103.siva: invalid argument" id=eb7040ac-3148-4a61-a86c-bdf811ab294e job=download source="downloader/download.go:61" url="https://github.com/src-d/notebooks"
time="2019-06-13T16:53:16.709913362+02:00" level=error msg=failed error="index read failed: seek /home/jfontan/work/gitcollector/sivas-new/f2/f281ab6f2e0e38dcc3af05360667d8f530c00103.siva: invalid argument" id=d1075a87-50fe-421e-9cda-b1c40ef5a14e job=download source="downloader/download.go:61" url="https://github.com/src-d/platform"
time="2019-06-13T16:53:16.724095577+02:00" level=error msg=failed error="index read failed: seek /home/jfontan/work/gitcollector/sivas-new/f2/f281ab6f2e0e38dcc3af05360667d8f530c00103.siva: invalid argument" id=7ef265a5-659a-4223-b790-d00e69f438a5 job=download source="downloader/download.go:61" url="https://github.com/src-d/guide"

Client also fails reading:

MySQL [(none)]> select * from repositories;
ERROR 1105 (HY000): unknown error: index read failed: seek /opt/repos/d2/d27a55c20fc832063a510bf70c90e2a7e977005a.siva: invalid argument

[mcarmonaa]

Same as #26