Bug#996171: glibmm2.4: FTBFS on buildds / reproducible builds without network access

[Aurelien Jarno]

Source: glibmm2.4
Version: 2.66.2-1
Severity: serious
Tags: upstream ftbfs
Justification: Debian Policy 4.9 

According to Debian Policy 4.9:

| For packages in the main archive, required targets must not attempt
| network access, except, via the loopback interface, to services on the
| build host that have been started by the build.

However the giomm_tls_client test in glibmm2.4 tries to connect to
https://www.gnome.org and fails to build if that host is not accessible:

| Summary of Failures:
| 
| 34/34 giomm_tls_client_test                TIMEOUT        30.03s   killed by signal 15 SIGTERM
| 
| 
| Ok:                 33  
| Expected Fail:      0   
| Fail:               0   
| Unexpected Pass:    0   
| Skipped:            0   
| Timeout:            1   
| dh_auto_test: error: cd obj-riscv64-linux-gnu && LC_ALL=C.UTF-8 MESON_TESTTHREADS=4 meson test returned exit code 1
| make: *** [debian/rules:7: build-arch] Error 25
| dpkg-buildpackage: error: debian/rules build-arch subprocess returned exit status 2

The full build log can be found there:
https://buildd.debian.org/status/fetch.php?pkg=glibmm2.4&arch=riscv64&ver=2.66.2-1&stamp=1633924088&raw=0

When instead the build happens with only the localhost interface, it
fails in a slightly different way:

| Summary of Failures:
| 
| 14/34 giomm_tls_client_test                FAIL            0.15s   killed by signal 6 SIGABRT
| 
| 
| Ok:                 33  
| Expected Fail:      0   
| Fail:               1   
| Unexpected Pass:    0   
| Skipped:            0   
| Timeout:            0   
| dh_auto_test: error: cd obj-x86_64-linux-gnu && LC_ALL=C.UTF-8 MESON_TESTTHREADS=15 meson test returned exit code 1
| make: *** [debian/rules:7: binary] Error 25
| dpkg-buildpackage: error: fakeroot debian/rules binary subprocess returned exit status 2
| 
| The full build log can be found there:
| https://tests.reproducible-builds.org/debian/rbuild/unstable/amd64/glibmm2.4_2.66.1-1.rbuild.log.gz