Daecho

@antz Quite reasonable, I'll have to dig through the travisci logs and see if I can figure out why it's working there.

I've been tripping over the same thing, trying to build three and four. zero->two work fine.

Been trying in:
* Clean 18.04 VM
* Clean 20.04 VM
* ubuntu:bionic docker image
* ubuntu:focal docker image
All with dedicated 6 cores and 16GB of RAM.

For testing/comparison:
 

# All as root
# Install Deps
apt-get -y update
apt-get -y install git make cmake libssl-dev libbz2-dev build-essential default-libmysqlclient-dev libace-6.4.5 libace-dev python

# Pull sources for zero->four
for MANGOS in 'zero' 'one' 'two' 'three' 'four'; do
    mkdir /${MANGOS}
    git clone --single-branch --recursive --depth 1 https://github.com/mangos${MANGOS}/server.git /${MANGOS}/server
    git clone --single-branch --recursive --depth 1 https://github.com/mangos${MANGOS}/database.git /${MANGOS}/db
    cd /${MANGOS}/server/dep && git pull origin master && git checkout master
    mkdir /${MANGOS}/build
done

# Try building zero->four
for MANGOS in 'zero' 'one' 'two' 'three' 'four'; do
    cd /${MANGOS}/build
    cmake ../server/ -DCMAKE_INSTALL_PREFIX=/mangos${MANGOS} -DCONF_INSTALL_DIR=/mangos${MANGOS}/etc -DPLAYERBOTS=0 -DSOAP=1
    make -j 1
done

zero - builds in all environments, can also be built with playerbots enabled in all environments
one - builds in all environments, playerbots is broken
two - builds in all environments, playerbots is broken
three - fails in all environments
four - fails in all environments

I've also tried SOAP on/off, clearly not related.

I actually have no idea how three passing travis right now.

Three and four give this(I've rerun a couple times since, so it's quicker to the ACE error)

root@e0b4347ae4f3:/three/build# cmake ../server/       -DCMAKE_INSTALL_PREFIX=/mangos       -DCONF_INSTALL_DIR=/mangos/etc       -DPLAYERBOTS=0       -DSOAP=0

This script builds the MaNGOS server.
  Options that can be used in order to configure the process:
   General:
    CMAKE_INSTALL_PREFIX    Path where the server should be installed to
    CONF_DIR                Path to the configs, can be absolute or relative.
    DEBUG                   Debug mode (strict compile, all warnings)
    ACE_USE_EXTERNAL        Use external ACE
    BUILD_MANGOSD           Build the main server
    BUILD_REALMD            Build the login server
    BUILD_TOOLS             Build the map/vmap/mmap extractors
    SOAP                    Enable remote access via SOAP
   Scripting engines:
    SCRIPT_LIB_ELUNA        Compile with support for Eluna scripts
    SCRIPT_LIB_SD3          Compile with support for ScriptDev3 scripts
#   Modules:
#    PLAYERBOTS              Enable Player Bots
  To set an option simply type -D<OPTION>=<VALUE> after 'cmake <srcs>'.
  Also, you can specify the generator with -G. see 'cmake --help' for more details
  For example: cmake .. -DDEBUG=1 -DCMAKE_INSTALL_PREFIX=/opt/mangos

  Note: On UNIX systems, CONF_DIR is relative to the bin folder.

-- Detected 64-bit platform
-- OpenSSL library: /usr/lib/x86_64-linux-gnu/libssl.so;/usr/lib/x86_64-linux-gnu/libcrypto.so
-- OpenSSL headers: /usr/include
-- OpenSSL version: 1.1.1
-- Install server to     : /mangosthree
-- Install configs to    : /mangosthree/etc/
-- Search configs from   : etc/
-- Support for SOAP      : No (default)
-- Script engine Eluna   : No (default)
-- Script engine SD3     : Yes (default)
-- Build main server     : Yes (default)
-- Build login server    : Yes (default)
-- Build tools           : Yes (default)
-- Build in debug-mode   : No  (default)
-- Configuring done
-- Generating done
-- Build files have been written to: /three/build
root@e0b4347ae4f3:/three/build# make -j1
[  0%] Built target pch.cpp_dephelp
[  0%] Built target generate_pch.cpp
[  0%] Building CXX object dep/acelite/CMakeFiles/ace.dir/ace/Log_Msg.cpp.o
/three/server/dep/acelite/ace/Log_Msg.cpp:438:30: error: 'ACE_DEFAULT_LOG_FLAGS' was not declared in this scope
 u_long ACE_Log_Msg::flags_ = ACE_DEFAULT_LOG_FLAGS;
                              ^~~~~~~~~~~~~~~~~~~~~
/three/server/dep/acelite/ace/Log_Msg.cpp:438:30: note: suggested alternative: 'ACE_DEFAULT_LOCALNAME'
 u_long ACE_Log_Msg::flags_ = ACE_DEFAULT_LOG_FLAGS;
                              ^~~~~~~~~~~~~~~~~~~~~
                              ACE_DEFAULT_LOCALNAME
dep/acelite/CMakeFiles/ace.dir/build.make:2438: recipe for target 'dep/acelite/CMakeFiles/ace.dir/ace/Log_Msg.cpp.o' failed
make[2]: *** [dep/acelite/CMakeFiles/ace.dir/ace/Log_Msg.cpp.o] Error 1
CMakeFiles/Makefile2:225: recipe for target 'dep/acelite/CMakeFiles/ace.dir/all' failed
make[1]: *** [dep/acelite/CMakeFiles/ace.dir/all] Error 2
Makefile:129: recipe for target 'all' failed
make: *** [all] Error 2