There seems to be some dependency issue between ebuilds.
On the chromiumos-sdk run for next day (https://uberchromegw.corp.google.com/i/chromiumos.tryserver/builders/chromiumos-sdk/builds/2852)
net-misc/openssh failed again, but this time during configure step with:

openssh-7.5_p1-r1: configure: error: *** OpenSSL headers missing - please install first or check config.log ***

Seems like a missing dependency to me. 

Builds after retrying at the end.

Retrying emerge of net-misc/openssh-7.5_p1-r1.
Started net-misc/openssh-7.5_p1-r1 (logged in /tmp/openssh-7.5_p1-r1-3QoUQ1)
Pending 12/656, Building 1/1, [Time 20:48:15 | Elapsed 115m8.2s | Load 1.58 5.35 16.2]
Still building openssh-7.5_p1-r1 (2m0.1s). Logs in /tmp/openssh-7.5_p1-r1-3QoUQ1
Completed net-misc/openssh-7.5_p1-r1 (in 2m57.8s)

And it completed on retry later:

Retrying emerge of net-misc/openssh-7.5_p1-r1.
Started net-misc/openssh-7.5_p1-r1 (logged in /tmp/openssh-7.5_p1-r1-reT0fT)
Completed net-misc/openssh-7.5_p1-r1 (in 2m57.3s)

openssh def depends on openssl:
LIB_DEPEND="
    ssl? (
        !libressl? (
            >=dev-libs/openssl-1.0.1:0=[bindist=]
            dev-libs/openssl:0=[static-libs(+)]
        )
        libressl? ( dev-libs/libressl:0=[static-libs(+)] )
    )
"
RDEPEND="!static? ( ${LIB_DEPEND//\[static-libs(+)]} )"
DEPEND="${RDEPEND}
    static? ( ${LIB_DEPEND} )"

that emerge output isn't the verbose style so it isn't showing us the USE flags up front (we should prob fix that), but if we look at the ebuild:
openssh-7.5_p1-r1: ./configure ... --with-ldflags=-Wl,-O2 -Wl,--as-needed -Wl,-O2 -Wl,--as-needed ... --with-openssl ...

so we know for sure it was built with USE='-static ssl'.

we also know from the build log that openssl was both built & installed before openssh was even started:
Started dev-libs/openssl-1.0.2n (logged in /tmp/openssl-1.0.2n-CCacwF)
Still building openssl-1.0.2n (2m1.7s). Logs in /tmp/openssl-1.0.2n-CCacwF
Still building openssl-1.0.2n (4m11.7s). Logs in /tmp/openssl-1.0.2n-CCacwF
Completed dev-libs/openssl-1.0.2n (in 4m36.1s)
Started net-misc/openssh-7.5_p1-r1 (logged in /tmp/openssh-7.5_p1-r1-Ffh9bi)
Still building openssh-7.5_p1-r1 (2m5.2s). Logs in /tmp/openssh-7.5_p1-r1-Ffh9bi
=== Start output for job openssh-7.5_p1-r1 (3m1.9s) ===
...failure...

so i doubt that's the issue.  it'd help if we had the config.log file though ... maybe we should change portage to dump that automatically when econf fails.

since this is not a toolchain issue, I dont think we should own this. 

Rahul, Can you please find an owner/label/component?