Strip whitespace characters from .ign patterns

Fixes bug #15902.

changelog

@@ -55,6 +55,7 @@ Version 1.9.0-svn:
    * Fixed the ping timeout not waiting for the default ping interval when
      ping timeout is not set to 0
    * Fixed a bug in scoring of AI recall list. Patch by billynux.
+   * Strip whitespace characters from .ign patterns (bug #15902)
  * Terrain animation related
    * animated terrain animations are not synchronized anymore
    * reworked macros to handle animations

src/addon_management.cpp

@@ -216,6 +216,7 @@ static std::pair<std::vector<std::string>, std::vector<std::string> > read_ignor
 	std::istream *stream = istream_file(ign_file);
 	std::string line;
 	while (std::getline(*stream, line)) {
+		utils::strip(line);
 		const size_t l = line.size();
 		if (line[l - 1] == '/') { // directory; we strip the last /
 			patterns.second.push_back(line.substr(0, l - 1));