Merge pull request #10328 from NixOS/backport-10325-to-2.21-maintenance

[Backport 2.21-maintenance] build-remote: fix format string shenanigans

src/build-remote/build-remote.cc

@@ -202,7 +202,7 @@ static int main_build_remote(int argc, char * * argv)
                         else
                             drvstr = "<unknown>";
 
-                        auto error = HintFmt(errorText);
+                        auto error = HintFmt::fromFormatString(errorText);
                         error
                             % drvstr
                             % neededSystem

src/libutil/fmt.hh

@@ -144,6 +144,10 @@ public:
         : HintFmt("%s", Uncolored(literal))
     { }
 
+    static HintFmt fromFormatString(const std::string & format) {
+        return HintFmt(boost::format(format));
+    }
+
     /**
      * Interpolate the given arguments into the format string.
      */