Changing the file type causes Maya to loose the scene name.

• If you open a scene, and change its file type (from ma to mb or vice versa), it will lose the scene name.
• If you open a scene, save the scene, then change the filetype, the bug doesn't show up.

import maya.cmds as mc

mc.file(r"C:/path/to/my/file.mb", open=True, force=True)
fileType1 = mc.file(query=True, type=True)
fileName1 = mc.file(query=True, sceneName=True)
print fileType1, fileName1
['mayaBinary'] C:/path/to/my/file.mb

# Change the file type:
mc.file(type='mayaAscii')

fileType2 = mc.file(query=True, type=True)
fileName2 = mc.file(query=True, sceneName=True)
print fileType2, fileName2
[u'mayaAscii']  # !!!! no more filename, it is an empty string !!!!!!!

import maya.cmds as mc

mc.file(r"C:/path/to/my/file.mb", open=True, force=True)
fileType1 = mc.file(query=True, type=True)
fileName1 = mc.file(query=True, sceneName=True)
print fileType1, fileName1
['mayaBinary'] C:/path/to/my/file.mb

# Save the file
mc.file(save=True, force=True)

# Change the file type:
mc.file(type='mayaAscii')

fileType2 = mc.file(query=True, type=True)
fileName2 = mc.file(query=True, sceneName=True)
print fileType2, fileName2
[u'mayaAscii'] C:/path/to/my/file.ma