api.detach_spawn failing locally, memcache.c:417.

[hgreving2304]

While debugging i#2694, I got this failure below twice. It seems to be very rare

<Application /usr/local/google/home/hgreving/dynamorio/build/suite/tests/bin/api.detach_spawn (166708). Internal Error: DynamoRIO debug check failure: /usr/local/google/home/hgreving/dynamorio/src/core/unix/memcache.c:417 found

xref #2694, #2623, #2690, same test.

[hgreving2304]

Seems to happen only w/ debug.

Occasionally, I am also getting this error:

<Application /home/hgreving/dynamorio/build/suite/tests/bin/api.detach_spawn_FLAKY (38683).  Internal Error: DynamoRIO debug check failure: /home/hgreving/dynamorio/src/core/heap.c:1497 IF_WINDOWS(doing_detach ||) heapmgt->vmheap.num_free_blocks == heapmgt->vmheap.num_blocks - unfreed_blocks || ((ever_beyond_vmm IF_WINDOWS(|| get_os_version() >= WINDOWS_VERSION_8_1)) && heapmgt

[hgreving2304]

Also exposed with api.detach_spawn_stress_FLAKY in 64 bit debug:

<Application /usr/local/google/home/hgreving/dynamorio/build/suite/tests/bin/api.detach_spawn_stress_FLAKY (210115).  Internal Error: DynamoRIO debug check failure: /usr/local/google/home/hgreving/dynamorio/src/core/unix/memcache.c:417 found
(Error occurred @784 frags)