flutter_tools/version: git log.showSignature=false (#38576)

diff --git a/packages/flutter_tools/lib/src/version.dart b/packages/flutter_tools/lib/src/version.dart
index 61666df..5afa883 100644
--- a/packages/flutter_tools/lib/src/version.dart
+++ b/packages/flutter_tools/lib/src/version.dart

@@ -20,7 +20,7 @@
 class FlutterVersion {
   @visibleForTesting
   FlutterVersion([this._clock = const SystemClock()]) {
-    _frameworkRevision = _runGit('git log -n 1 --pretty=format:%H');
+    _frameworkRevision = _runGit(gitLog(<String>['-n', '1', '--pretty=format:%H']).join(' '));
     _frameworkVersion = GitTagVersion.determine().frameworkVersionFor(_frameworkRevision);
   }
 
@@ -86,7 +86,7 @@
 
   String _frameworkAge;
   String get frameworkAge {
-    return _frameworkAge ??= _runGit('git log -n 1 --pretty=format:%ar');
+    return _frameworkAge ??= _runGit(gitLog(<String>['-n', '1', '--pretty=format:%ar']).join(' '));
   }
 
   String _frameworkVersion;
@@ -134,15 +134,13 @@
   String get frameworkCommitDate => _latestGitCommitDate();
 
   static String _latestGitCommitDate([ String branch ]) {
-    final List<String> args = <String>[
-      'git',
-      'log',
+    final List<String> args = gitLog(<String>[
       if (branch != null) branch,
       '-n',
       '1',
       '--pretty=format:%ad',
       '--date=iso',
-    ];
+    ]);
     return _runSync(args, lenient: false);
   }
 
@@ -332,6 +330,14 @@
     }
   }
 
+  /// log.showSignature=false is a user setting and it will break things,
+  /// so we want to disable it for every git log call.  This is a convenience
+  /// wrapper that does that.
+  @visibleForTesting
+  static List<String> gitLog(List<String> args) {
+    return <String>['git', '-c', 'log.showSignature=false', 'log'] + args;
+  }
+
   @visibleForTesting
   static String versionOutOfDateMessage(Duration frameworkAge) {
     String warning = 'WARNING: your installation of Flutter is ${frameworkAge.inDays} days old.';

diff --git a/packages/flutter_tools/test/general.shard/commands/version_test.dart b/packages/flutter_tools/test/general.shard/commands/version_test.dart
index 304e3e0..c09ff69 100644
--- a/packages/flutter_tools/test/general.shard/commands/version_test.dart
+++ b/packages/flutter_tools/test/general.shard/commands/version_test.dart

@@ -10,6 +10,7 @@
 import 'package:flutter_tools/src/base/io.dart';
 import 'package:flutter_tools/src/cache.dart';
 import 'package:flutter_tools/src/commands/version.dart';
+import 'package:flutter_tools/src/version.dart';
 import 'package:mockito/mockito.dart';
 import 'package:process/process.dart';
 
@@ -116,7 +117,7 @@
     Encoding stderrEncoding = systemEncoding,
   }) {
     final String commandStr = command.join(' ');
-    if (commandStr == 'git log -n 1 --pretty=format:%H') {
+    if (commandStr == FlutterVersion.gitLog(<String>['-n', '1', '--pretty=format:%H']).join(' ')) {
       return ProcessResult(0, 0, '000000000000000000000', '');
     }
     if (commandStr ==

diff --git a/packages/flutter_tools/test/general.shard/runner/flutter_command_runner_test.dart b/packages/flutter_tools/test/general.shard/runner/flutter_command_runner_test.dart
index a5c5541..50df260 100644
--- a/packages/flutter_tools/test/general.shard/runner/flutter_command_runner_test.dart
+++ b/packages/flutter_tools/test/general.shard/runner/flutter_command_runner_test.dart

@@ -132,7 +132,7 @@
       testUsingContext('checks that Flutter toJson output reports the flutter framework version', () async {
         final ProcessResult result = ProcessResult(0, 0, 'random', '0');
 
-        when(processManager.runSync('git log -n 1 --pretty=format:%H'.split(' '),
+        when(processManager.runSync(FlutterVersion.gitLog('-n 1 --pretty=format:%H'.split(' ')),
           workingDirectory: Cache.flutterRoot)).thenReturn(result);
         when(processManager.runSync('git rev-parse --abbrev-ref --symbolic @{u}'.split(' '),
           workingDirectory: Cache.flutterRoot)).thenReturn(result);
@@ -140,11 +140,11 @@
           workingDirectory: Cache.flutterRoot)).thenReturn(result);
         when(processManager.runSync('git ls-remote --get-url master'.split(' '),
           workingDirectory: Cache.flutterRoot)).thenReturn(result);
-        when(processManager.runSync('git log -n 1 --pretty=format:%ar'.split(' '),
+        when(processManager.runSync(FlutterVersion.gitLog('-n 1 --pretty=format:%ar'.split(' ')),
           workingDirectory: Cache.flutterRoot)).thenReturn(result);
         when(processManager.runSync('git describe --match v*.*.* --first-parent --long --tags'.split(' '),
           workingDirectory: Cache.flutterRoot)).thenReturn(result);
-        when(processManager.runSync('git log -n 1 --pretty=format:%ad --date=iso'.split(' '),
+        when(processManager.runSync(FlutterVersion.gitLog('-n 1 --pretty=format:%ad --date=iso'.split(' ')),
           workingDirectory: Cache.flutterRoot)).thenReturn(result);
 
         final FakeFlutterVersion version = FakeFlutterVersion();

diff --git a/packages/flutter_tools/test/general.shard/version_test.dart b/packages/flutter_tools/test/general.shard/version_test.dart
index 1a94470..b438fec 100644
--- a/packages/flutter_tools/test/general.shard/version_test.dart
+++ b/packages/flutter_tools/test/general.shard/version_test.dart

@@ -465,14 +465,18 @@
   });
 
   final Answering<ProcessResult> syncAnswer = (Invocation invocation) {
-    bool argsAre(String a1, [ String a2, String a3, String a4, String a5, String a6, String a7, String a8 ]) {
+    bool argsAre(String a1, [ String a2, String a3, String a4, String a5, String a6, String a7, String a8, String a9 ]) {
       const ListEquality<String> equality = ListEquality<String>();
       final List<String> args = invocation.positionalArguments.single;
-      final List<String> expectedArgs = <String>[a1, a2, a3, a4, a5, a6, a7, a8].where((String arg) => arg != null).toList();
+      final List<String> expectedArgs = <String>[a1, a2, a3, a4, a5, a6, a7, a8, a9].where((String arg) => arg != null).toList();
       return equality.equals(args, expectedArgs);
     }
 
-    if (argsAre('git', 'log', '-n', '1', '--pretty=format:%ad', '--date=iso')) {
+    bool listArgsAre(List<String> a) {
+      return Function.apply(argsAre, a);
+    }
+
+    if (listArgsAre(FlutterVersion.gitLog(<String>['-n', '1', '--pretty=format:%ad', '--date=iso']))) {
       return success(localCommitDate.toString());
     } else if (argsAre('git', 'remote')) {
       return success('');
@@ -483,7 +487,8 @@
         fail('Did not expect server ping');
       }
       return errorOnFetch ? failure(128) : success('');
-    } else if (remoteCommitDate != null && argsAre('git', 'log', '__flutter_version_check__/$channel', '-n', '1', '--pretty=format:%ad', '--date=iso')) {
+    // Careful here!  argsAre accepts 9 arguments and FlutterVersion.gitLog adds 4.
+    } else if (remoteCommitDate != null && listArgsAre(FlutterVersion.gitLog(<String>['__flutter_version_check__/$channel', '-n', '1', '--pretty=format:%ad', '--date=iso']))) {
       return success(remoteCommitDate.toString());
     }
 
@@ -506,12 +511,12 @@
     environment: anyNamed('environment'),
   )).thenReturn(ProcessResult(102, 0, 'branch', ''));
   when(pm.runSync(
-    <String>['git', 'log', '-n', '1', '--pretty=format:%H'],
+    FlutterVersion.gitLog(<String>['-n', '1', '--pretty=format:%H']),
     workingDirectory: anyNamed('workingDirectory'),
     environment: anyNamed('environment'),
   )).thenReturn(ProcessResult(103, 0, '1234abcd', ''));
   when(pm.runSync(
-    <String>['git', 'log', '-n', '1', '--pretty=format:%ar'],
+    FlutterVersion.gitLog(<String>['-n', '1', '--pretty=format:%ar']),
     workingDirectory: anyNamed('workingDirectory'),
     environment: anyNamed('environment'),
   )).thenReturn(ProcessResult(104, 0, '1 second ago', ''));