git-gui: Perform our own magic shbang detection on Windows

diff --git a/git-gui.sh b/git-gui.sh
index 9b342f08464c39d7096c987f3444772770962370..7e6952c2bc0d31e8028f80573b846af90be9dc6f 100755 (executable)
--- a/git-gui.sh
+++ b/git-gui.sh
@@ -294,6 +294,7 @@ proc _git_cmd {name} {
 
        if {[catch {set v $_git_cmd_path($name)}]} {
                switch -- $name {
+                 version   -
                --version   -
                --exec-path { return [list $::_git $name] }
                }
@@ -301,19 +302,31 @@ proc _git_cmd {name} {
                set p [gitexec git-$name$::_search_exe]
                if {[file exists $p]} {
                        set v [list $p]
-               } elseif {[is_Cygwin]} {
-                       # On Cygwin git is a proper Cygwin program and knows
-                       # how to properly restart the Cygwin environment and
-                       # spawn its non-.exe support program.
+               } elseif {[is_Windows] && [file exists [gitexec git-$name]]} {
+                       # Try to determine what sort of magic will make
+                       # git-$name go and do its thing, because native
+                       # Tcl on Windows doesn't know it.
                        #
-                       set v [list $::_git $name]
-               } elseif {[is_Windows]
-                       && $::_sh ne {}
-                       && [file exists [gitexec git-$name]]} {
-                       # Assume this is a UNIX shell script.  We can
-                       # probably execute it through a Bourne shell.
-                       #
-                       set v [list $::_sh [gitexec git-$name]]
+                       set p [gitexec git-$name]
+                       set f [open $p r]
+                       set s [gets $f]
+                       close $f
+
+                       switch -glob -- $s {
+                       #!*sh     { set i sh     }
+                       #!*perl   { set i perl   }
+                       #!*python { set i python }
+                       default   { error "git-$name is not supported: $s" }
+                       }
+
+                       upvar #0 _$i interp
+                       if {![info exists interp]} {
+                               set interp [_which $i]
+                       }
+                       if {$interp eq {}} {
+                               error "git-$name requires $i (not in PATH)"
+                       }
+                       set v [list $interp $p]
                } else {
                        # Assume it is builtin to git somehow and we
                        # aren't actually able to see a file for it.
@@ -505,7 +518,6 @@ if {$_git eq {}} {
        exit 1
 }
 set _nice [_which nice]
-set _sh   [_which sh]
 
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