This is blocking the compiler upgrade which is needed for some security patches.  
We have been waiting for a compiler upgrade for at least 10 days and we thought it was going to happen today. 
We need a fix for this ASAP. 
Do we know what caused this? 

dgarrett@ suggested we copied bmgordon@ just in case.

bmgordon@, jclinton@ can you please take a look and see if any of your changes could explain this? 

This CL:

https://chromium-review.googlesource.com/c/chromiumos/chromite/+/912467

could have uprevved things that were pending for uprev and maybe one of those may explain the problem (I am not sure).

I took a look a few hours ago and didn't see anything that could be related to anything that either of us have touched. I've been trying to push through a Python upgrade but haven't been able to land that CL yet.

This has an easy local reproducer (after a fresh repo sync):

$ cros_sdk --delete
$ cros_sdk --bootstrap

Fails within 10 minutes, and with the same error.
This makes it unlikely that the error has anything to do with the environment on the builder itself.

Something strange is happening when emerging portage itself:

I started a tryjob without quiet and emerge cannot find portage dependencies.

INFO    cros_sdk:make_chroot: Updating portage
env: ccache: No such file or directory
!!! Section 'gentoo' in repos.conf has location attribute set to nonexistent directory: '/usr/portage'
!!! Invalid Repository Location (not a dir): '/usr/portage'
WARNING: One or more repositories have missing repo_name entries:
	/usr/local/portage/crossdev/profiles/repo_name
	/mnt/host/source/src/third_party/chromiumos-overlay/profiles/repo_name
	/mnt/host/source/src/third_party/eclass-overlay/profiles/repo_name
	/mnt/host/source/src/third_party/portage-stable/profiles/repo_name
NOTE: Each repo_name entry should be a plain text file containing a
unique name for the repository on the first line.
These are the packages that would be merged, in order:
Calculating dependencies  ... done!
Total: 0 packages, Size of downloads: 0 kB
!!! The following update(s) have been skipped due to unsatisfied dependencies
!!! triggered by backtracking:
sys-apps/portage:0
Nothing to merge; quitting.


Previously, this part used to build 54 packages.

I think this is because of the curl upgrade. Will test and report back.

https://chromium-review.googlesource.com/c/chromiumos/overlays/portage-stable/+/919534 drop EAPI to 5. That should hopefully fix the problem.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/overlays/portage-stable/+/0bb293fb7b211880848f73a6a0caf0309ea5f7fb

commit 0bb293fb7b211880848f73a6a0caf0309ea5f7fb
Author: Manoj Gupta <manojgupta@google.com>
Date: Wed Feb 14 23:03:37 2018

curl: set EAPI to 5.

curl is emerged very early before portage that supported EAPI=6 is available.
The older portage version does not support EAPI=6 so set EAPI to 5..
Change eapply to epatch as eapply is not available in "5"..

BUG= chromium:812342 
TEST=curl still builds.
TEST=https://uberchromegw.corp.google.com/i/chromiumos.tryserver/builders/chromiumos-sdk/builds/2902

Change-Id: Ibd0ba90f1dee88ef12cd01760370f06773d1f15d
Reviewed-on: https://chromium-review.googlesource.com/919534
Tested-by: Manoj Gupta <manojgupta@chromium.org>
Trybot-Ready: Manoj Gupta <manojgupta@chromium.org>
Reviewed-by: Manoj Gupta <manojgupta@chromium.org>
Reviewed-by: Rahul Chaudhry <rahulchaudhry@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Reviewed-by: Jason Clinton <jclinton@chromium.org>
Reviewed-by: Brian Norris <briannorris@chromium.org>

[rename] https://crrev.com/0bb293fb7b211880848f73a6a0caf0309ea5f7fb/net-misc/curl/curl-7.58.0-r1.ebuild

InitSDK completed in latest chromiumos-sdk run: https://uberchromegw.corp.google.com/i/chromiumos/builders/chromiumos-sdk/builds/8542