don't add default compressors two times if disabled

This is in so far pointless as the first match will deal with the
extension, so we don't actually ever use these second instances –
probably for the better as most need arguments to behave as epected &
more importantly: the point of the exercise disabling their use for
testing proposes.

Gbp-Dch: Ignore

apt-pkg/aptconfiguration.cc

@@ -365,42 +365,45 @@ const Configuration::getCompressors(bool const Cached) {
 
 	setDefaultConfigurationForCompressors();
 
-	compressors.push_back(Compressor(".", "", "", NULL, NULL, 0));
+	std::vector<std::string> CompressorsDone;
+# define APT_ADD_COMPRESSOR(NAME, EXT, BINARY, ARG, DEARG, COST) \
+	{ CompressorsDone.push_back(NAME); compressors.emplace_back(NAME, EXT, BINARY, ARG, DEARG, COST); }
+	APT_ADD_COMPRESSOR(".", "", "", nullptr, nullptr, 0)
 	if (_config->Exists("Dir::Bin::lz4") == false || FileExists(_config->Find("Dir::Bin::lz4")) == true)
-		compressors.push_back(Compressor("lz4",".lz4","lz4","-1","-d",50));
+		APT_ADD_COMPRESSOR("lz4",".lz4","lz4","-1","-d",50)
 #ifdef HAVE_LZ4
 	else
-		compressors.push_back(Compressor("lz4",".lz4","false", NULL, NULL, 50));
+		APT_ADD_COMPRESSOR("lz4",".lz4","false", nullptr, nullptr, 50)
 #endif
 	if (_config->Exists("Dir::Bin::gzip") == false || FileExists(_config->Find("Dir::Bin::gzip")) == true)
-		compressors.push_back(Compressor("gzip",".gz","gzip","-6n","-d",100));
+		APT_ADD_COMPRESSOR("gzip",".gz","gzip","-6n","-d",100)
 #ifdef HAVE_ZLIB
 	else
-		compressors.push_back(Compressor("gzip",".gz","false", NULL, NULL, 100));
+		APT_ADD_COMPRESSOR("gzip",".gz","false", nullptr, nullptr, 100)
 #endif
 	if (_config->Exists("Dir::Bin::xz") == false || FileExists(_config->Find("Dir::Bin::xz")) == true)
-		compressors.push_back(Compressor("xz",".xz","xz","-6","-d",200));
+		APT_ADD_COMPRESSOR("xz",".xz","xz","-6","-d",200)
 #ifdef HAVE_LZMA
 	else
-		compressors.push_back(Compressor("xz",".xz","false", NULL, NULL, 200));
+		APT_ADD_COMPRESSOR("xz",".xz","false", nullptr, nullptr, 200)
 #endif
 	if (_config->Exists("Dir::Bin::bzip2") == false || FileExists(_config->Find("Dir::Bin::bzip2")) == true)
-		compressors.push_back(Compressor("bzip2",".bz2","bzip2","-6","-d",300));
+		APT_ADD_COMPRESSOR("bzip2",".bz2","bzip2","-6","-d",300)
 #ifdef HAVE_BZ2
 	else
-		compressors.push_back(Compressor("bzip2",".bz2","false", NULL, NULL, 300));
+		APT_ADD_COMPRESSOR("bzip2",".bz2","false", nullptr, nullptr, 300)
 #endif
 	if (_config->Exists("Dir::Bin::lzma") == false || FileExists(_config->Find("Dir::Bin::lzma")) == true)
-		compressors.push_back(Compressor("lzma",".lzma","lzma","-6","-d",400));
+		APT_ADD_COMPRESSOR("lzma",".lzma","lzma","-6","-d",400)
 #ifdef HAVE_LZMA
 	else
-		compressors.push_back(Compressor("lzma",".lzma","false", NULL, NULL, 400));
+		APT_ADD_COMPRESSOR("lzma",".lzma","false", nullptr, nullptr, 400)
 #endif
 
 	std::vector<std::string> const comp = _config->FindVector("APT::Compressor", "", true);
 	for (auto const &c: comp)
 	{
-		if (c.empty() || std::any_of(compressors.begin(), compressors.end(), [&c](Compressor const &ac) { return ac.Name == c; }))
+		if (c.empty() || std::find(CompressorsDone.begin(), CompressorsDone.end(), c) != CompressorsDone.end())
 			continue;
 		compressors.push_back(Compressor(c.c_str(), std::string(".").append(c).c_str(), c.c_str(), nullptr, nullptr, 1000));
 	}