Spurious failure building apr-utils in core-updates

[Mark H Weaver <mhw@netris.org>]

I encountered a spurious failure while building apr-utils in
core-updates on x86_64.  Simply repeating the same build completed
successfully, with the same hash as the failed.  Here's the log tail of
the failure:

--8<---------------cut here---------------start------------->8---
/gnu/store/z8adi2ci2ygaqaykfr537jly2fxq4vh4-bash-4.3/bin/bash /gnu/store/nfycgk0b18bka5s7j6pa4i9zvqgmfczb-apr-1.4.8/build-1/libtool --silent --mode=compile gcc -g -O2 -pthread   -DHAVE_CONFIG_H -DLINUX -D_REENTRANT -D_GNU_SOURCE   -I/tmp/nix-build-apr-util-1.5.2.drv-1/apr-util-1.5.2/include -I/tmp/nix-build-apr-util-1.5.2.drv-1/apr-util-1.5.2/include/private  -I/gnu/store/nfycgk0b18bka5s7j6pa4i9zvqgmfczb-apr-1.4.8/include/apr-1  -I/tmp/nix-build-apr-util-1.5.2.drv-1/apr-util-1.5.2/xml/expat/lib  -o testqueue.lo -c testqueue.c && touch testqueue.lo
/gnu/store/z8adi2ci2ygaqaykfr537jly2fxq4vh4-bash-4.3/bin/bash /gnu/store/nfycgk0b18bka5s7j6pa4i9zvqgmfczb-apr-1.4.8/build-1/libtool --silent --mode=link gcc -g -O2 -pthread   -DHAVE_CONFIG_H -DLINUX -D_REENTRANT -D_GNU_SOURCE   -I/tmp/nix-build-apr-util-1.5.2.drv-1/apr-util-1.5.2/include -I/tmp/nix-build-apr-util-1.5.2.drv-1/apr-util-1.5.2/include/private  -I/gnu/store/nfycgk0b18bka5s7j6pa4i9zvqgmfczb-apr-1.4.8/include/apr-1  -I/tmp/nix-build-apr-util-1.5.2.drv-1/apr-util-1.5.2/xml/expat/lib      -no-install  -o dbd dbd.lo ../libaprutil-1.la /tmp/nix-build-apr-util-1.5.2.drv-1/apr-util-1.5.2/xml/expat/libexpat.la /gnu/store/nfycgk0b18bka5s7j6pa4i9zvqgmfczb-apr-1.4.8/lib/libapr-1.la -lrt -lcrypt -lpthread -ldl
/gnu/store/z8adi2ci2ygaqaykfr537jly2fxq4vh4-bash-4.3/bin/bash /gnu/store/nfycgk0b18bka5s7j6pa4i9zvqgmfczb-apr-1.4.8/build-1/libtool --silent --mode=compile gcc -g -O2 -pthread   -DHAVE_CONFIG_H -DLINUX -D_REENTRANT -D_GNU_SOURCE   -I/tmp/nix-build-apr-util-1.5.2.drv-1/apr-util-1.5.2/include -I/tmp/nix-build-apr-util-1.5.2.drv-1/apr-util-1.5.2/include/private  -I/gnu/store/nfycgk0b18bka5s7j6pa4i9zvqgmfczb-apr-1.4.8/include/apr-1  -I/tmp/nix-build-apr-util-1.5.2.drv-1/apr-util-1.5.2/xml/expat/lib  -o testmemcache.lo -c testmemcache.c && touch testmemcache.lo
/gnu/store/z8adi2ci2ygaqaykfr537jly2fxq4vh4-bash-4.3/bin/bash /gnu/store/nfycgk0b18bka5s7j6pa4i9zvqgmfczb-apr-1.4.8/build-1/libtool --silent --mode=link gcc -g -O2 -pthread   -DHAVE_CONFIG_H -DLINUX -D_REENTRANT -D_GNU_SOURCE   -I/tmp/nix-build-apr-util-1.5.2.drv-1/apr-util-1.5.2/include -I/tmp/nix-build-apr-util-1.5.2.drv-1/apr-util-1.5.2/include/private  -I/gnu/store/nfycgk0b18bka5s7j6pa4i9zvqgmfczb-apr-1.4.8/include/apr-1  -I/tmp/nix-build-apr-util-1.5.2.drv-1/apr-util-1.5.2/xml/expat/lib      -no-install  -o testall abts.lo testutil.lo teststrmatch.lo testuri.lo testuuid.lo testbuckets.lo testpass.lo testmd4.lo testmd5.lo testldap.lo testdate.lo testdbm.lo testdbd.lo testxml.lo testrmm.lo testreslist.lo testqueue.lo testxlate.lo testmemcache.lo testcrypto.lo ../libaprutil-1.la /tmp/nix
 -build-apr-util-1.5.2.drv-1/apr-util-1.5.2/xml/expat/libexpat.la /gnu/store/nfycgk0b18bka5s7j6pa4i9zvqgmfczb-apr-1.4.8/lib/libapr-1.la -lrt -lcrypt -lpthread -ldl 
libtool: link: `testmemcache.lo' is not a valid libtool object
Makefile:50: recipe for target 'testall' failed
make[2]: *** [testall] Error 1
make[2]: Leaving directory '/tmp/nix-build-apr-util-1.5.2.drv-1/apr-util-1.5.2/test'
/tmp/nix-build-apr-util-1.5.2.drv-1/apr-util-1.5.2/build/rules.mk:114: recipe for target 'all-recursive' failed
make[1]: *** [all-recursive] Error 1
make[1]: *** Waiting for unfinished jobs....
make[1]: Leaving directory '/tmp/nix-build-apr-util-1.5.2.drv-1/apr-util-1.5.2/test'
Makefile:121: recipe for target 'check' failed
make: *** [check] Error 2
phase `check' failed after 10 seconds
--8<---------------cut here---------------end--------------->8---

I've saved the failed build directory, as well as complete logs of the
failed build and the later successful one.

Here's 'testmemcache.lo' from the failed build directory:

--8<---------------cut here---------------start------------->8---
# testmemcache.lo - a libtool object file
# Generated by libtool (GNU libtool) 2.4.2
#
# Please DO NOT delete this file!
# It is necessary for linking the library.

# Name of the PIC object.
pic_object='.libs/testmemcache.o'

# Name of the non-PIC object
non_pic_object='testmemcache.o'

--8<---------------cut here---------------end--------------->8---

I guess I should also mention that I was building from a local
core-updates branch with some additional commits: guile upgraded to
2.0.11, some cherry-picked patches from master, and some doc fixes that
I've posted but not yet pushed:

--8<---------------cut here---------------start------------->8---
Commits in HEAD
4a14613 * [core-updates] apr-utils-failure gnu: cmake: Install man pages and docs in share/{man,doc}.
a4b20a2 * gnu: openssh: Upgrade to 6.6p1.
273fe5f * gnu: flac: Install man pages in share/man.
45ad817 * gnu: guile: Upgrade to 2.0.11.
8105ea6 * gnu: lynx: Upgrade to 2.8.8rel.2.
afe6be4 * gnu: bc: Install docs in share/man and share/info.
69b34af * gnu: unzip: Install man pages in share/man.
9bbe414 * gnu: screen: Install docs in share/man and share/info.
6209a2d * gnu: netcat: Install docs in share/man and share/info.
a380c24 * gnu: xterm: Upgrade to 303.
12fa800 * [origin/core-updates] gnu: util-macros: Install .pc file in lib/pkgconfig; remove INSTALL file.
--8<---------------cut here---------------end--------------->8---

However, I very much doubt that any of these commits are relevant to
this problem.

Any ideas?

     Mark