Log Message:
Update go115 to 1.15.13.

go1.15.13 (released 2021-06-03) includes security fixes to the archive/zip,
math/big, net, and net/http/httputil packages, as well as bug fixes to the
linker, the go command, and the math/big and net/http packages. See the Go
1.15.13 milestone on our issue tracker for details.

The SetString and UnmarshalText methods of math/big.Rat
<https://pkg.go.dev/math/big#Rat> may cause a panic or an unrecoverable
fatal error if passed inputs with very large exponents.
This is issue <https://github.com/golang/go/issues/44910> and
CVE-2021-33198.

Thanks to the OSS-Fuzz project for discovering this issue and to Emmanuel
Odeke for reporting it.

ReverseProxy in net/http/httputil <https://pkg.go.dev/net/http/httputil> could
be made to forward certain hop-by-hop headers, including Connection. In
case the target of the ReverseProxy was itself a reverse proxy, this would
let an attacker drop arbitrary headers, including those set by the
ReverseProxy.Director.
This is issue <https://github.com/golang/go/issues/46313> and
CVE-2021-33197.

Thanks to Mattias Grenfeldt (https://grenfeldt.dev) and Asta Olofsson for
reporting this issue.

The LookupCNAME, LookupSRV, LookupMX, LookupNS, and LookupAddr functions in
net <https://pkg.go.dev/net>, and their respective methods on the Resolver
<https://pkg.go.dev/net#Resolver> type may return arbitrary values
retrieved from DNS which do not follow the established RFC 1035
<https://datatracker.ietf.org/doc/html/rfc1035>rules for domain names. If
these names are used without further sanitization, for instance unsafely
included in HTML, they may allow for injection of unexpected content. Note
that LookupTXT may still return arbitrary values that could require
sanitization before further use.
This is issue <https://github.com/golang/go/issues/46241> and
CVE-2021-33195.

Thanks to Philipp Jeitner and Haya Shulman from Fraunhofer SIT for
reporting this issue.

The NewReader and OpenReader functions in archive/zip
<https://pkg.go.dev/archive/zip> can cause a panic or an unrecoverable
fatal error when reading an archive that claims to contain a large number
of files, regardless of its actual size.
This is issue <https://github.com/golang/go/issues/46242>and
CVE-2021-33196.

Thanks to the OSS-Fuzz project for discovering this issue and to Emmanuel
Odeke for reporting it.