file: backport patch to fix a 5.39 regression

This bug is causing diffoscope to fail to build with file 5.39.

pkgs/tools/misc/file/default.nix

@@ -12,6 +12,12 @@ stdenv.mkDerivation rec {
     sha256 = "1lgs2w2sgamzf27kz5h7pajz7v62554q21fbs11n4mfrfrm2hpgh";
   };
 
+  patches = [
+    # https://github.com/file/file/commit/85b7ab83257b3191a1a7ca044589a092bcef2bb3
+    # Without the RCS id change to avoid conflicts. Remove on next bump.
+    ./webassembly-format-fix.patch
+  ];
+
   nativeBuildInputs = stdenv.lib.optional (stdenv.hostPlatform != stdenv.buildPlatform) file;
   buildInputs = [ zlib ]
               ++ stdenv.lib.optional stdenv.hostPlatform.isWindows libgnurx;

pkgs/tools/misc/file/webassembly-format-fix.patch

@@ -0,0 +1,13 @@
+diff --git a/src/funcs.c b/src/funcs.c
+index 299b8f022..ecbfa28c5 100644
+--- a/src/funcs.c
++++ b/src/funcs.c
+@@ -93,7 +93,7 @@ file_checkfmt(char *msg, size_t mlen, const char *fmt)
+ 		if (*++p == '%')
+ 			continue;
+ 		// Skip uninteresting.
+-		while (strchr("0.'+- ", *p) != NULL)
++		while (strchr("#0.'+- ", *p) != NULL)
+ 			p++;
+ 		if (*p == '*') {
+ 			if (msg)