Write the command to execute in the error message so people don't have to learn how svn works.

presubmit_canned_checks.py

Index: presubmit_canned_checks.py
diff --git a/presubmit_canned_checks.py b/presubmit_canned_checks.py
index dd3313196c137438f98d45859ee891f148ac1e7d..138ed75bf2cebb314878462775862f62d3ba9fc6 100755
--- a/presubmit_canned_checks.py
+++ b/presubmit_canned_checks.py
@@ -194,10 +194,12 @@ def CheckChangeSvnEolStyle(input_api, output_api, source_file_filter=None):
   if bad:
     if input_api.is_committing:
       return [output_api.PresubmitError(
-            "Fix these files with svn svn:eol-style=LF", items=bad)]
+            "Run `svn pset svn:eol-style LF <item>` on these files:",
+            items=bad)]
     else:
       return [output_api.PresubmitNotifyResult(
-            "Fix these files with svn svn:eol-style=LF", items=bad)]
+            "Run `svn pset svn:eol-style LF <item>` on these files:",
+            items=bad)]
   return []