Address Jason's comments

Author: daxian-dbw

PSReadLine/Cmdlets.cs

@@ -8,7 +8,6 @@
 using System.Collections.ObjectModel;
 using System.Diagnostics.CodeAnalysis;
 using System.Globalization;
-using System.IO;
 using System.Management.Automation;
 using System.Management.Automation.Language;
 using System.Reflection;
@@ -639,9 +638,7 @@ public string HistorySavePath
             get => _historySavePath;
             set
             {
-                // Normalize the path
-                var altPathChar = RuntimeInformation.IsOSPlatform(OSPlatform.Windows) ? '/' : '\\';
-                _historySavePath = value?.Replace(altPathChar, Path.DirectorySeparatorChar);
+                _historySavePath = GetUnresolvedProviderPathFromPSPath(value);
             }
         }
         private string _historySavePath;

PSReadLine/History.cs

@@ -7,6 +7,7 @@
 using System.Diagnostics;
 using System.IO;
 using System.Linq;
+using System.Runtime.InteropServices;
 using System.Text;
 using System.Threading;
 using Microsoft.PowerShell.PSReadLine;
@@ -22,20 +23,20 @@ internal class FNV1a32Hash
         private const uint FNV32_PRIME = 16777619;
         private const uint FNV32_OFFSETBASIS = 2166136261;
 
-        internal static uint ComputeHash(byte[] buffer)
+        internal static uint ComputeHash(string input)
         {
             uint hash = FNV32_OFFSETBASIS;
-            for (int i = 0; i < buffer.Length; i++)
+            for (int i = 0; i < input.Length; i++)
             {
-                hash = (hash ^ buffer[i]) * FNV32_PRIME;
+                char c = input[i];
+                uint lowByte = (uint)(c & 0x00FF);
+                hash = (hash ^ lowByte) * FNV32_PRIME;
+
+                uint highByte = (uint)(c >> 8);
+                hash = (hash ^ highByte) * FNV32_PRIME;
             }
             return hash;
         }
-
-        internal static uint ComputeHash(string input)
-        {
-            return ComputeHash(Encoding.UTF8.GetBytes(input));
-        }
     }
 
     public partial class PSConsoleReadLine
@@ -171,7 +172,12 @@ private string GetHistorySaveFileMutexName()
         {
             // Return a reasonably unique name - it's not too important as there will rarely
             // be any contention.
-            return "PSReadLineHistoryFile_" + FNV1a32Hash.ComputeHash(_options.HistorySavePath);
+            uint hashFromPath = FNV1a32Hash.ComputeHash(
+                RuntimeInformation.IsOSPlatform(OSPlatform.Windows)
+                    ? _options.HistorySavePath.ToLower()
+                    : _options.HistorySavePath);
+
+            return "PSReadLineHistoryFile_" + hashFromPath.ToString();
         }
 
         private void IncrementalHistoryWrite()