XML reformatter sometimes requires multiple tries

[klauer]

Issue

This hook: https://github.com/pcdshub/pre-commit-hooks/blob/master/pre_commit_hooks/xml_format.py#L1
sometimes requires multiple tries to properly reformat:

• First try: reformats partially
• Second try: reformats fully
• Third try: allows you to commit

We should double-check the code - potentially reformatting with multiple iterations or increasing some parameter to the existing call to dive deeper into the XML.

[ZLLentz]

Here's of one example of a diff that only includes changes made on the second try, as maybe a clue:

diff --git a/lcls-plc-example-motion/tc_mot_example/tc_mot_example.tmc b/lcls-plc-example-motion/tc_mot_example/tc_mot_example.tmc
index 3ceeaa9..ecd31d7 100644
--- a/lcls-plc-example-motion/tc_mot_example/tc_mot_example.tmc
+++ b/lcls-plc-example-motion/tc_mot_example/tc_mot_example.tmc
@@ -4252,7 +4252,7 @@
       </Method>
       <Method>
         <Name>Write</Name>
-        <Comment>
+        <Comment>
     Writes the contents of the buffer into a file.
 </Comment>
         <ReturnType Namespace="LCLS_General.TcUnit.SysDir.SysTypes">RTS_IEC_RESULT</ReturnType>
@@ -4379,7 +4379,7 @@
       </Method>
       <Method>
         <Name>Find</Name>
-        <Comment>
+        <Comment>
     Find a searchstring in the buffer and returns its position.
     It's possible to add a preffered startposition within buffer
 </Comment>
@@ -4466,7 +4466,7 @@
       </Method>
       <Method>
         <Name>Clear</Name>
-        <Comment>
+        <Comment>
     Clears the buffer and sets the length to 0
 </Comment>
         <Local>
@@ -4919,7 +4919,7 @@
       </Method>
       <Method>
         <Name>ClearBuffer</Name>
-        <Comment>
+        <Comment>
     Clears the contents of the entire buffer.
 </Comment>
       </Method>

I personally can't figure out what's different yet

[ZLLentz]

After a closer inspection, there is a single space after in these three multiline comment blocks after the first reformat, but not after the second.

[ZLLentz]

I have two suggestions:

1. have the parser function run itself on its output a few times
2. strip whitespace from the end of every line in the output