Please include relevant excerpts from the build logs, or attach it, since koji will delete this information after some time.

   Doc-tests regex
     Running `/usr/bin/rustdoc --test /builddir/build/BUILD/regex-0.2.3/src/lib.rs --crate-name regex -L dependency=/builddir/build/BUILD/regex-0.2.3/target/release/deps -L dependency=/builddir/build/BUILD/regex-0.2.3/target/release/deps --extern memchr=/builddir/build/BUILD/regex-0.2.3/target/release/deps/libmemchr-100633f14af7898e.rlib --extern thread_local=/builddir/build/BUILD/regex-0.2.3/target/release/deps/libthread_local-0bc04cd85e2c2b4a.rlib --extern aho_corasick=/builddir/build/BUILD/regex-0.2.3/target/release/deps/libaho_corasick-54dc3ad9c44d661e.rlib --extern regex_syntax=/builddir/build/BUILD/regex-0.2.3/target/release/deps/libregex_syntax-a845a3d2da639bc4.rlib --extern utf8_ranges=/builddir/build/BUILD/regex-0.2.3/target/release/deps/libutf8_ranges-eeea8f97f730146c.rlib --extern quickcheck=/builddir/build/BUILD/regex-0.2.3/target/release/deps/libquickcheck-c43b1b310468ce63.rlib --extern lazy_static=/builddir/build/BUILD/regex-0.2.3/target/release/deps/liblazy_static-61f635f4fba6a1fe.rlib --extern regex=/builddir/build/BUILD/regex-0.2.3/target/release/deps/libregex-25d33714accd320d.rlib --extern rand=/builddir/build/BUILD/regex-0.2.3/target/release/deps/librand-5a6d34673da5ea43.rlib`
running 59 tests
test src/compile.rs - compile::Compiler::c (line 241) ... ignored
test src/dfa.rs - dfa::StatePtr (line 361) ... ignored
test src/re_set.rs - re_set::bytes::RegexSet (line 78) ... ignored
test src/re_set.rs - re_set::unicode::RegexSet (line 78) ... ignored
test src/re_unicode.rs - re_unicode::Regex (line 127) ... ignored
fatal runtime error: allocator memory exhausted
fatal runtime error: allocator memory exhausted
error: process didn't exit successfully: `/usr/bin/rustdoc --test /builddir/build/BUILD/regex-0.2.3/src/lib.rs --crate-name regex -L dependency=/builddir/build/BUILD/regex-0.2.3/target/release/deps -L dependency=/builddir/build/BUILD/regex-0.2.3/target/release/deps --extern memchr=/builddir/build/BUILD/regex-0.2.3/target/release/deps/libmemchr-100633f14af7898e.rlib --extern thread_local=/builddir/build/BUILD/regex-0.2.3/target/release/deps/libthread_local-0bc04cd85e2c2b4a.rlib --extern aho_corasick=/builddir/build/BUILD/regex-0.2.3/target/release/deps/libaho_corasick-54dc3ad9c44d661e.rlib --extern regex_syntax=/builddir/build/BUILD/regex-0.2.3/target/release/deps/libregex_syntax-a845a3d2da639bc4.rlib --extern utf8_ranges=/builddir/build/BUILD/regex-0.2.3/target/release/deps/libutf8_ranges-eeea8f97f730146c.rlib --extern quickcheck=/builddir/build/BUILD/regex-0.2.3/target/release/deps/libquickcheck-c43b1b310468ce63.rlib --extern lazy_static=/builddir/build/BUILD/regex-0.2.3/target/release/deps/liblazy_static-61f635f4fba6a1fe.rlib --extern regex=/builddir/build/BUILD/regex-0.2.3/target/release/deps/libregex-25d33714accd320d.rlib --extern rand=/builddir/build/BUILD/regex-0.2.3/target/release/deps/librand-5a6d34673da5ea43.rlib` (signal: 4, SIGILL: illegal instruction)


One thing we're doing a little differently is running tests in release mode.  We may want to rethink this.  For one, it turns off debug-assertions and overflow checks, which you'd usually want to have in test cases.  But besides that, tests are often generated in a myriad of combinations, which can mean a lot more code to optimize than you'd have in practical use cases.

This bug appears to have been reported against 'rawhide' during the Fedora 28 development cycle.
Changing version to '28'.

Just happened on http crate..

   Doc-tests http
     Running `/usr/bin/rustdoc --test /builddir/build/BUILD/http-0.1.5/src/lib.rs --crate-name http -L dependency=/builddir/build/BUILD/http-0.1.5/target/release/deps -L dependency=/builddir/build/BUILD/http-0.1.5/target/release/deps --extern seahash=/builddir/build/BUILD/http-0.1.5/target/release/deps/libseahash-75798b077f6861d7.rlib --extern bytes=/builddir/build/BUILD/http-0.1.5/target/release/deps/libbytes-68d0a619d155bc54.rlib --extern quickcheck=/builddir/build/BUILD/http-0.1.5/target/release/deps/libquickcheck-4853578852fd35b4.rlib --extern http=/builddir/build/BUILD/http-0.1.5/target/release/deps/libhttp-7140b7cce70a75e8.rlib --extern serde=/builddir/build/BUILD/http-0.1.5/target/release/deps/libserde-44830541608951e6.rlib --extern ordermap=/builddir/build/BUILD/http-0.1.5/target/release/deps/libordermap-c3405a3f8a5c324e.rlib --extern fnv=/builddir/build/BUILD/http-0.1.5/target/release/deps/libfnv-f483af183b65834f.rlib --extern serde_json=/builddir/build/BUILD/http-0.1.5/target/release/deps/libserde_json-d9cabac435a7127a.rlib --extern rand=/builddir/build/BUILD/http-0.1.5/target/release/deps/librand-13232c3168ec0484.rlib`
running 186 tests
fatal runtime error: allocator memory exhausted
error: process didn't exit successfully: `/usr/bin/rustdoc --test /builddir/build/BUILD/http-0.1.5/src/lib.rs --crate-name http -L dependency=/builddir/build/BUILD/http-0.1.5/target/release/deps -L dependency=/builddir/build/BUILD/http-0.1.5/target/release/deps --extern seahash=/builddir/build/BUILD/http-0.1.5/target/release/deps/libseahash-75798b077f6861d7.rlib --extern bytes=/builddir/build/BUILD/http-0.1.5/target/release/deps/libbytes-68d0a619d155bc54.rlib --extern quickcheck=/builddir/build/BUILD/http-0.1.5/target/release/deps/libquickcheck-4853578852fd35b4.rlib --extern http=/builddir/build/BUILD/http-0.1.5/target/release/deps/libhttp-7140b7cce70a75e8.rlib --extern serde=/builddir/build/BUILD/http-0.1.5/target/release/deps/libserde-44830541608951e6.rlib --extern ordermap=/builddir/build/BUILD/http-0.1.5/target/release/deps/libordermap-c3405a3f8a5c324e.rlib --extern fnv=/builddir/build/BUILD/http-0.1.5/target/release/deps/libfnv-f483af183b65834f.rlib --extern serde_json=/builddir/build/BUILD/http-0.1.5/target/release/deps/libserde_json-d9cabac435a7127a.rlib --extern rand=/builddir/build/BUILD/http-0.1.5/target/release/deps/librand-13232c3168ec0484.rlib` (signal: 4, SIGILL: illegal instruction)

Doesn't seem to happen anymore.