[QGIS-Developer] Error building QGIS server withouth GUI

[Tom Palan]

Hello everybody,

we are using QGIS server on our servers, without any GUI. For this I
built a single Debian package without the desktop components and
deployed on the servers. We are using currently version 2.18, but want
to make the switch to 3.4 in the next few weeks, also for participating
more in the dev process.

My problem is with building QGIS 3.4.4:
when I specify the cmake paramters like this:
cmake -G Ninja \
      -DCMAKE_VERBOSE_MAKEFILE=1 \
        -DCMAKE_INSTALL_PREFIX=/usr \
        -DBINDINGS_GLOBAL_INSTALL=TRUE \
        -DPEDANTIC=TRUE \
        -DSERVER_SKIP_ECW=TRUE \
        -DQGIS_CGIBIN_SUBDIR=/usr/lib/cgi-bin \
        -DWITH_APIDOC=TRUE \
        -DGENERATE_QHP=TRUE \
        -DWITH_CUSTOM_WIDGETS=FALSE \
        -DWITH_GLOBE=FALSE \
        -DWITH_SERVER=TRUE \
        -DWITH_SERVER_PLUGINS=TRUE \
        -DWITH_QWTPOLAR=FALSE \
        -DWITH_DESKTOP=FALSE \
        -DWITH_GUI=TRUE \
        -DDOXYGEN_ON_DEMAND=TRUE ..

everything builds correctly.
But with WITH_GUI=FALSE the build fails with the following error:
ninja: error:
'../python/plugins/db_manager/db_plugins/postgis/plugins/versioning/pyg
ui', needed by
'python/plugins/db_manager/db_plugins/postgis/plugins/versioning/ui_Dlg
Versioning.py', missing and no known rule to make it

I am not sure what WITH_GUI does in the end, but as I want to remove
any unnecessary components (and therefore install dependencies), please
could somebody point me in the right direction? Thanks!

Tom Palan