git-gui: handle config booleans without value

When git interprets a config variable without a value as bool it is considered
as true. But git-gui doesn't so until yet.

The value for boolean configs are also case-insensitive.

Signed-off-by: Bert Wesarg <bert.wesarg@googlemail.com>
Signed-off-by: Pat Thoyts <patthoyts@users.sourceforge.net>
diff --git a/git-gui.sh b/git-gui.sh
index e5dd8bc..33ab5dc 100755
--- a/git-gui.sh
+++ b/git-gui.sh
@@ -299,7 +299,9 @@
 	global repo_config
 	if {[catch {set v $repo_config($name)}]} {
 		return 0
-	} elseif {$v eq {true} || $v eq {1} || $v eq {yes}} {
+	}
+	set v [string tolower $v]
+	if {$v eq {} || $v eq {true} || $v eq {1} || $v eq {yes} || $v eq {on}} {
 		return 1
 	} else {
 		return 0
@@ -310,7 +312,9 @@
 	global repo_config
 	if {[catch {set v $repo_config($name)}]} {
 		return 0
-	} elseif {$v eq {false} || $v eq {0} || $v eq {no}} {
+	}
+	set v [string tolower $v]
+	if {$v eq {false} || $v eq {0} || $v eq {no} || $v eq {off}} {
 		return 1
 	} else {
 		return 0
@@ -1060,6 +1064,10 @@
 				} else {
 					set arr($name) $value
 				}
+			} elseif {[regexp {^([^\n]+)$} $line line name]} {
+				# no value given, but interpreting them as
+				# boolean will be handled as true
+				set arr($name) {}
 			}
 		}
 	}
@@ -1075,6 +1083,10 @@
 					} else {
 						set arr($name) $value
 					}
+				} elseif {[regexp {^([^=]+)$} $line line name]} {
+					# no value given, but interpreting them as
+					# boolean will be handled as true
+					set arr($name) {}
 				}
 			}
 			close $fd_rc