multibuild misses dependencies

[bmwiedemann]

Reproducer:

osc co openSUSE:Factory/pg_cron && cd $_
osc build --noservice --clean -M postgresql95 --local-package
osc build --noservice --clean -M postgresql95 --alternative-project $PRJ

Such a build misses the postgresql95-server-devel dependency and thus the build fails with
make: pg_config: Command not found

A workaround is to patch the spec file to work without -M

other affected packages might be imb, kicad-doc, mvapich2 and tensorflow

[bmwiedemann]

I captured debug output from

osc -d build --noservice --clean -M openmpi --local-package > /tmp/osc.debug.bad 2>&1
osc -d build --noservice --clean -M openmpi > /tmp/osc.debug.good 2>&1

and the only diff in API calls was

--- /tmp/osc.debug.bad  2019-05-27 14:29:05.779602037 +0000
+++ /tmp/osc.debug.good 2019-05-27 14:28:28.599574781 +0000
-POST https://api.opensuse.org/build/openSUSE:Factory/standard/x86_64/_repository/_buildinfo
+POST https://api.opensuse.org/build/openSUSE:Factory/standard/x86_64/imb:openmpi/_buildinfo
 ...
-[   15s] [126/126] cumulate gcc-c++-9-1.1
+[   14s] [156/156] cumulate openmpi-devel-1.10.7-21.2

and osc api /build/openSUSE:Factory/standard/x86_64/_repository/_buildinfo returns

Server returned an error: HTTP Error 404: Not Found
openSUSE:Factory/_repository

osc api -X POST -f imb.spec /build/openSUSE:Factory/standard/x86_64/_repository:imb-openmpi/_buildinfo
Server returned an error: HTTP Error 400: Bad Request
packid '_repository' is illegal

And that might be why it ends up with 30 fewer packages installed in the build environment.